From 88ac5b42a6b20f104ecf913dfb970a2b0abd2b4a Mon Sep 17 00:00:00 2001
From: Andy Phan <andyphan@chromium.org>
Date: Fri, 10 Jul 2026 15:37:39 -0700
Subject: [PATCH] [mime_handler] Validate URL during MIME handler fallback re-navigation

When a generic MIME handler (such as a 3p extension) aborts and triggers
fallback, it initiates a reload of the embedder frame. The response body
of the initial request is cached and later spliced into the reload
response by PluginResponseInterceptorURLLoaderThrottle.

Previously, this lookup was keyed only by the FrameTreeNodeId. If the
reload was redirected (e.g. HTTP 302) to a different origin by the
attacker's server, the attacker-controlled cached body could be spliced
under the victim's URL, leading to address bar spoofing.

Fix the issue by storing the original URL for which the fallback body
was cached. When WillProcessResponse is called, the throttle now passes
the response URL, and the manager validates that it matches (ignoring
ref) the cached original URL. If they mismatch, the cached body is
discarded and the reload falls back to the network.

Bug: 519244446
Change-Id: I21a70d101dbcbe5878e80bcda7b6316fc579fe35
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/8031969
Reviewed-by: Devlin Cronin <rdevlin.cronin@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Andy Phan <andyphan@chromium.org>
Reviewed-by: Maksim Sisov <msisov@igalia.com>
Cr-Commit-Position: refs/heads/main@{#1660567}
---

diff --git a/chrome/browser/extensions/api/mime_handlers/mime_handler_fallback_browsertest.cc b/chrome/browser/extensions/api/mime_handlers/mime_handler_fallback_browsertest.cc
index c1da100..d4ac4ec 100644
--- a/chrome/browser/extensions/api/mime_handlers/mime_handler_fallback_browsertest.cc
+++ b/chrome/browser/extensions/api/mime_handlers/mime_handler_fallback_browsertest.cc
@@ -6,10 +6,12 @@
 #include <string_view>
 
 #include "base/files/file_path.h"
+#include "base/files/file_util.h"
 #include "base/path_service.h"
 #include "base/strings/strcat.h"
 #include "base/test/scoped_feature_list.h"
 #include "base/test/with_feature_override.h"
+#include "base/threading/thread_restrictions.h"
 #include "chrome/browser/extensions/extension_apitest.h"
 #include "chrome/browser/pdf/pdf_extension_test_util.h"
 #include "chrome/browser/ui/browser.h"
@@ -27,6 +29,7 @@
 #include "extensions/common/extension_features.h"
 #include "extensions/common/features/feature_channel.h"
 #include "net/dns/mock_host_resolver.h"
+#include "net/test/embedded_test_server/controllable_http_response.h"
 #include "pdf/pdf_features.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "url/gurl.h"
@@ -318,6 +321,119 @@
   EXPECT_EQ(pdf_url, web_contents->GetLastCommittedURL());
 }
 
+class MimeHandlerFallbackRedirectBrowserTest
+    : public MimeHandlerFallbackBrowserTest {
+ public:
+  MimeHandlerFallbackRedirectBrowserTest() = default;
+
+ protected:
+  void SetUpOnMainThread() override {
+    const base::FilePath chrome_test_data_dir =
+        base::PathService::CheckedGet(chrome::DIR_TEST_DATA);
+    const base::FilePath pdf_path =
+        chrome_test_data_dir.AppendASCII("pdf").AppendASCII("test.pdf");
+    ASSERT_TRUE(base::PathExists(pdf_path));
+    {
+      base::ScopedAllowBlockingForTesting allow_blocking;
+      ASSERT_TRUE(base::ReadFileToString(pdf_path, &pdf_data_));
+    }
+
+    // Register controllable responses before starting the server. Expect two
+    // requests to "/spoof.pdf".
+    controllable_response1_ =
+        std::make_unique<net::test_server::ControllableHttpResponse>(
+            embedded_test_server(), "/spoof.pdf");
+    controllable_response2_ =
+        std::make_unique<net::test_server::ControllableHttpResponse>(
+            embedded_test_server(), "/spoof.pdf");
+
+    MimeHandlerFallbackBrowserTest::SetUpOnMainThread();
+  }
+
+  const std::string& pdf_data() const { return pdf_data_; }
+
+  net::test_server::ControllableHttpResponse* controllable_response1() {
+    return controllable_response1_.get();
+  }
+
+  net::test_server::ControllableHttpResponse* controllable_response2() {
+    return controllable_response2_.get();
+  }
+
+ private:
+  std::string pdf_data_;
+  std::unique_ptr<net::test_server::ControllableHttpResponse>
+      controllable_response1_;
+  std::unique_ptr<net::test_server::ControllableHttpResponse>
+      controllable_response2_;
+};
+
+// Verify that fallback reload redirected to a different origin does not use the
+// cached body, preventing spoofing.
+IN_PROC_BROWSER_TEST_P(MimeHandlerFallbackRedirectBrowserTest,
+                       FallbackRedirectToDifferentOriginDoesNotUseCache) {
+  if (!chrome_pdf::features::IsOopifPdfEnabled()) {
+    GTEST_SKIP() << "Cached-body fallback routing is OOPIF-only.";
+  }
+
+  ASSERT_NO_FATAL_FAILURE(LoadThirdPartyHandler());
+  content::WebContents* const web_contents =
+      browser()->tab_strip_model()->GetActiveWebContents();
+
+  const GURL start_url = embedded_test_server()->GetURL("a.com", "/spoof.pdf");
+
+  const auto pdf_extension_observer = MakePdfExtensionObserver();
+
+  // Start navigation (non-blocking).
+  web_contents->GetController().LoadURLWithParams(
+      content::NavigationController::LoadURLParams(start_url));
+
+  // 1. Handle first request (attacker PDF).
+  net::test_server::ControllableHttpResponse* response1 =
+      controllable_response1();
+  response1->WaitForRequest();
+  response1->Send("HTTP/1.1 200 OK\r\n");
+  response1->Send("Content-Type: application/pdf\r\n");
+  response1->Send("\r\n");
+  response1->Send(pdf_data());
+  response1->Done();
+
+  // 2. Handle second request (fallback reload redirected to b.com).
+  net::test_server::ControllableHttpResponse* response2 =
+      controllable_response2();
+  response2->WaitForRequest();
+  const GURL target_url =
+      embedded_test_server()->GetURL("b.com", "/accessibility/multi-page.pdf");
+  response2->Send("HTTP/1.1 302 Found\r\n");
+  response2->Send("Location: " + target_url.spec() + "\r\n");
+  response2->Send("\r\n");
+  response2->Done();
+
+  // Now wait for the navigation to settle.
+  pdf_extension_observer->WaitForNavigationFinished();
+  ASSERT_TRUE(content::WaitForLoadStop(web_contents));
+
+  content::RenderFrameHost* const extension_host =
+      pdf_extension_test_util::GetOnlyPdfExtensionHost(web_contents);
+  ASSERT_TRUE(extension_host);
+
+  // Verify that the PDF has loaded.
+  EXPECT_TRUE(pdf_extension_test_util::EnsurePDFHasLoaded(web_contents));
+
+  // Get the page count.
+  const int page_count =
+      content::EvalJs(extension_host, "viewer.docLength_").ExtractInt();
+
+  // test.pdf has 1 page. accessibility/multi-page.pdf has 2 pages. Expect the
+  // browser to load the redirected PDF (multi-page, 2 pages). If spoofing
+  // occurs, the browser loads the cached PDF (test.pdf, 1 page).
+  EXPECT_EQ(2, page_count);
+
+  // Also verify the committed URL is the redirected one.
+  EXPECT_EQ(target_url, web_contents->GetLastCommittedURL());
+}
+
 INSTANTIATE_FEATURE_OVERRIDE_TEST_SUITE(MimeHandlerFallbackBrowserTest);
+INSTANTIATE_FEATURE_OVERRIDE_TEST_SUITE(MimeHandlerFallbackRedirectBrowserTest);
 
 }  // namespace extensions
diff --git a/chrome/browser/plugins/plugin_response_interceptor_url_loader_throttle.cc b/chrome/browser/plugins/plugin_response_interceptor_url_loader_throttle.cc
index 40d2176..7b53b59 100644
--- a/chrome/browser/plugins/plugin_response_interceptor_url_loader_throttle.cc
+++ b/chrome/browser/plugins/plugin_response_interceptor_url_loader_throttle.cc
@@ -167,25 +167,24 @@
   if (response_head->mime_type == pdf::kPDFMimeType) {
     // A generic MIME handler extension called
     // chrome.mimeHandler.abortAndFallbackToNativeHandler() on a prior
-    // navigation for this embedder frame. Peek (not consume) at the
-    // fallback mark so the aborted extension does not re-claim its own
-    // response across the whole redirect chain -- the mark is cleared in
-    // `DidFinishNavigation()` once the re-fetch settles. Route the
-    // application/pdf response to the user agent's built-in PDF viewer.
-    // When the prior stream buffered the response body, take it now and
-    // replay it below instead of re-reading the reload's network body.
-    // The cached body is consumable only by the OOPIF PDF stream
-    // pipeline; the legacy MimeHandlerView GuestView path has no hook
-    // for a pre-fetched body pipe, so leave the pipe parked and let the
-    // reload re-fetch from the network.
+    // navigation for this embedder frame. Peek (not consume) at the fallback
+    // mark so the aborted extension does not re-claim its own response on
+    // reload -- the mark is cleared in `DidFinishNavigation()` once the
+    // re-fetch settles. Route the application/pdf response to the user agent's
+    // built-in PDF viewer. When the prior stream buffered the response body,

diff --git a/chrome/browser/extensions/api/mime_handlers/mime_handler_fallback_browsertest.cc b/chrome/browser/extensions/api/mime_handlers/mime_handler_fallback_browsertest.cc
index c1da100..d4ac4ec 100644
--- a/chrome/browser/extensions/api/mime_handlers/mime_handler_fallback_browsertest.cc
+++ b/chrome/browser/extensions/api/mime_handlers/mime_handler_fallback_browsertest.cc
@@ -6,10 +6,12 @@
 #include <string_view>
 
 #include "base/files/file_path.h"
+#include "base/files/file_util.h"
 #include "base/path_service.h"
 #include "base/strings/strcat.h"
 #include "base/test/scoped_feature_list.h"
 #include "base/test/with_feature_override.h"
+#include "base/threading/thread_restrictions.h"
 #include "chrome/browser/extensions/extension_apitest.h"
 #include "chrome/browser/pdf/pdf_extension_test_util.h"
 #include "chrome/browser/ui/browser.h"
@@ -27,6 +29,7 @@
 #include "extensions/common/extension_features.h"
 #include "extensions/common/features/feature_channel.h"
 #include "net/dns/mock_host_resolver.h"
+#include "net/test/embedded_test_server/controllable_http_response.h"
 #include "pdf/pdf_features.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "url/gurl.h"
@@ -318,6 +321,119 @@
   EXPECT_EQ(pdf_url, web_contents->GetLastCommittedURL());
 }
 
+class MimeHandlerFallbackRedirectBrowserTest
+    : public MimeHandlerFallbackBrowserTest {
+ public:
+  MimeHandlerFallbackRedirectBrowserTest() = default;
+
+ protected:
+  void SetUpOnMainThread() override {
+    const base::FilePath chrome_test_data_dir =
+        base::PathService::CheckedGet(chrome::DIR_TEST_DATA);
+    const base::FilePath pdf_path =
+        chrome_test_data_dir.AppendASCII("pdf").AppendASCII("test.pdf");
+    ASSERT_TRUE(base::PathExists(pdf_path));
+    {
+      base::ScopedAllowBlockingForTesting allow_blocking;
+      ASSERT_TRUE(base::ReadFileToString(pdf_path, &pdf_data_));
+    }
+
+    // Register controllable responses before starting the server. Expect two
+    // requests to "/spoof.pdf".
+    controllable_response1_ =
+        std::make_unique<net::test_server::ControllableHttpResponse>(
+            embedded_test_server(), "/spoof.pdf");
+    controllable_response2_ =
+        std::make_unique<net::test_server::ControllableHttpResponse>(
+            embedded_test_server(), "/spoof.pdf");
+
+    MimeHandlerFallbackBrowserTest::SetUpOnMainThread();
+  }
+
+  const std::string& pdf_data() const { return pdf_data_; }
+
+  net::test_server::ControllableHttpResponse* controllable_response1() {
+    return controllable_response1_.get();
+  }
+
+  net::test_server::ControllableHttpResponse* controllable_response2() {
+    return controllable_response2_.get();
+  }
+
+ private:
+  std::string pdf_data_;
+  std::unique_ptr<net::test_server::ControllableHttpResponse>
+      controllable_response1_;
+  std::unique_ptr<net::test_server::ControllableHttpResponse>
+      controllable_response2_;
+};
+
+// Verify that fallback reload redirected to a different origin does not use the
+// cached body, preventing spoofing.
+IN_PROC_BROWSER_TEST_P(MimeHandlerFallbackRedirectBrowserTest,
+                       FallbackRedirectToDifferentOriginDoesNotUseCache) {
+  if (!chrome_pdf::features::IsOopifPdfEnabled()) {
+    GTEST_SKIP() << "Cached-body fallback routing is OOPIF-only.";
+  }
+
+  ASSERT_NO_FATAL_FAILURE(LoadThirdPartyHandler());
+  content::WebContents* const web_contents =
+      browser()->tab_strip_model()->GetActiveWebContents();
+
+  const GURL start_url = embedded_test_server()->GetURL("a.com", "/spoof.pdf");
+
+  const auto pdf_extension_observer = MakePdfExtensionObserver();
+
+  // Start navigation (non-blocking).
+  web_contents->GetController().LoadURLWithParams(
+      content::NavigationController::LoadURLParams(start_url));
+
+  // 1. Handle first request (attacker PDF).
+  net::test_server::ControllableHttpResponse* response1 =
+      controllable_response1();
+  response1->WaitForRequest();
+  response1->Send("HTTP/1.1 200 OK\r\n");
+  response1->Send("Content-Type: application/pdf\r\n");
+  response1->Send("\r\n");
+  response1->Send(pdf_data());
+  response1->Done();
+
+  // 2. Handle second request (fallback reload redirected to b.com).
+  net::test_server::ControllableHttpResponse* response2 =
+      controllable_response2();
+  response2->WaitForRequest();
+  const GURL target_url =
+      embedded_test_server()->GetURL("b.com", "/accessibility/multi-page.pdf");
+  response2->Send("HTTP/1.1 302 Found\r\n");
+  response2->Send("Location: " + target_url.spec() + "\r\n");
+  response2->Send("\r\n");
+  response2->Done();
+
+  // Now wait for the navigation to settle.
+  pdf_extension_observer->WaitForNavigationFinished();
+  ASSERT_TRUE(content::WaitForLoadStop(web_contents));
+
+  content::RenderFrameHost* const extension_host =
+      pdf_extension_test_util::GetOnlyPdfExtensionHost(web_contents);
+  ASSERT_TRUE(extension_host);
+
+  // Verify that the PDF has loaded.
+  EXPECT_TRUE(pdf_extension_test_util::EnsurePDFHasLoaded(web_contents));
+
+  // Get the page count.
+  const int page_count =
+      content::EvalJs(extension_host, "viewer.docLength_").ExtractInt();
+
+  // test.pdf has 1 page. accessibility/multi-page.pdf has 2 pages. Expect the
+  // browser to load the redirected PDF (multi-page, 2 pages). If spoofing
+  // occurs, the browser loads the cached PDF (test.pdf, 1 page).
+  EXPECT_EQ(2, page_count);
+
+  // Also verify the committed URL is the redirected one.
+  EXPECT_EQ(target_url, web_contents->GetLastCommittedURL());
+}
+
 INSTANTIATE_FEATURE_OVERRIDE_TEST_SUITE(MimeHandlerFallbackBrowserTest);
+INSTANTIATE_FEATURE_OVERRIDE_TEST_SUITE(MimeHandlerFallbackRedirectBrowserTest);
 
 }  // namespace extensions
diff --git a/extensions/browser/api/mime_handler/mime_handler_api_unittest.cc b/extensions/browser/api/mime_handler/mime_handler_api_unittest.cc
index 229d7b4..329f96b 100644
--- a/extensions/browser/api/mime_handler/mime_handler_api_unittest.cc
+++ b/extensions/browser/api/mime_handler/mime_handler_api_unittest.cc
@@ -268,7 +268,7 @@
   stream_info->SetDidExtensionFinishNavigation();
 
   const content::FrameTreeNodeId embedder_ftn = embedder->GetFrameTreeNodeId();
-  ASSERT_FALSE(manager->IsPendingNativeFallback(embedder_ftn));
+  ASSERT_FALSE(manager->IsPendingNativeFallback(embedder_ftn, kOriginalUrl));
 
   auto function = base::MakeRefCounted<
       MimeHandlerAbortAndFallbackToNativeHandlerFunction>();
@@ -277,7 +277,7 @@
   EXPECT_TRUE(
       api_test_utils::RunFunction(function.get(), "[]", browser_context()));
   EXPECT_TRUE(function->GetError().empty()) << function->GetError();
-  EXPECT_TRUE(manager->IsPendingNativeFallback(embedder_ftn));
+  EXPECT_TRUE(manager->IsPendingNativeFallback(embedder_ftn, kOriginalUrl));
 }
 
 // Built-in MIME handler extensions (e.g. the PDF viewer) are blocked
diff --git a/extensions/browser/mime_handler/mime_handler_stream_manager_unittest.cc b/extensions/browser/mime_handler/mime_handler_stream_manager_unittest.cc
index 27e82501f..01f5a43 100644
--- a/extensions/browser/mime_handler/mime_handler_stream_manager_unittest.cc
+++ b/extensions/browser/mime_handler/mime_handler_stream_manager_unittest.cc
@@ -1207,8 +1207,10 @@
 
 TEST_F(MimeHandlerStreamManagerTest,
        AbortAndFallbackToNativeHandler_MarksEmbedderFrame) {
+  const GURL pdf_url(kOriginalUrl1);
+
   content::RenderFrameHost* embedder_host =
-      NavigateAndCommit(main_rfh(), GURL(kOriginalUrl1));
+      NavigateAndCommit(main_rfh(), pdf_url);
   const content::FrameTreeNodeId embedder_ftn =
       embedder_host->GetFrameTreeNodeId();
   auto* manager = mime_handler_stream_manager();
@@ -1225,23 +1227,25 @@
   ASSERT_TRUE(stream_info);
   stream_info->SetDidExtensionFinishNavigation();
 
-  EXPECT_FALSE(manager->IsPendingNativeFallback(embedder_ftn));
+  EXPECT_FALSE(manager->IsPendingNativeFallback(embedder_ftn, pdf_url));
   manager->AbortAndFallbackToNativeHandler(embedder_host);
 
-  // Peek is non-destructive -- the throttle's `WillProcessResponse`
-  // may fire multiple times in a single re-navigation (redirect chain),
-  // so the mark must survive until the navigation completes.
-  EXPECT_TRUE(manager->IsPendingNativeFallback(embedder_ftn));
-  EXPECT_TRUE(manager->IsPendingNativeFallback(embedder_ftn));
+  // Peek is non-destructive -- the mark must survive until the navigation
+  // completes.
+  EXPECT_TRUE(manager->IsPendingNativeFallback(embedder_ftn, pdf_url));
+  EXPECT_TRUE(manager->IsPendingNativeFallback(embedder_ftn, pdf_url));
 
   // A different frame is never marked.
-  EXPECT_FALSE(manager->IsPendingNativeFallback(content::FrameTreeNodeId()));
+  EXPECT_FALSE(
+      manager->IsPendingNativeFallback(content::FrameTreeNodeId(), pdf_url));
 }
 
 TEST_F(MimeHandlerStreamManagerTest,
        AbortAndFallbackToNativeHandler_DidFinishNavigationClearsMark) {
+  const GURL pdf_url(kOriginalUrl1);
+
   content::RenderFrameHost* embedder_host =
-      NavigateAndCommit(main_rfh(), GURL(kOriginalUrl1));
+      NavigateAndCommit(main_rfh(), pdf_url);
   const content::FrameTreeNodeId embedder_ftn =
       embedder_host->GetFrameTreeNodeId();
   auto* manager = mime_handler_stream_manager();
@@ -1255,23 +1259,25 @@
   stream_info->SetDidExtensionFinishNavigation();
 
   manager->AbortAndFallbackToNativeHandler(embedder_host);
-  ASSERT_TRUE(manager->IsPendingNativeFallback(embedder_ftn));
+  ASSERT_TRUE(manager->IsPendingNativeFallback(embedder_ftn, pdf_url));
 
   // `DidFinishNavigation` on the embedder FTN clears the mark --
   // committed or errored, the re-fetch is over.
   NiceMock<content::MockNavigationHandle> finish_handle(web_contents());
   finish_handle.set_render_frame_host(embedder_host);
   manager->DidFinishNavigation(&finish_handle);
-  EXPECT_FALSE(manager->IsPendingNativeFallback(embedder_ftn));
+  EXPECT_FALSE(manager->IsPendingNativeFallback(embedder_ftn, pdf_url));
 }
 
 TEST_F(MimeHandlerStreamManagerTest,
        AbortAndFallbackToNativeHandler_NoBodyCache_TakeReturnsInvalid) {
+  const GURL pdf_url(kOriginalUrl1);
+
   // Without a body cache attached, the FTN mark still exists but the
   // captured handle is invalid -- the throttle will fall through to a
   // network refetch.
   content::RenderFrameHost* embedder_host =
-      NavigateAndCommit(main_rfh(), GURL(kOriginalUrl1));
+      NavigateAndCommit(main_rfh(), pdf_url);
   const content::FrameTreeNodeId embedder_ftn =
       embedder_host->GetFrameTreeNodeId();
   auto* manager = mime_handler_stream_manager();
@@ -1285,12 +1291,15 @@
   stream_info->SetDidExtensionFinishNavigation();
 
   manager->AbortAndFallbackToNativeHandler(embedder_host);
-  ASSERT_TRUE(manager->IsPendingNativeFallback(embedder_ftn));
-  EXPECT_FALSE(manager->TakeCachedFallbackBody(embedder_ftn).has_value());
+  ASSERT_TRUE(manager->IsPendingNativeFallback(embedder_ftn, pdf_url));
+  EXPECT_FALSE(
+      manager->TakeCachedFallbackBody(embedder_ftn, pdf_url).has_value());
 }
 
 TEST_F(MimeHandlerStreamManagerTest,
        AbortAndFallbackToNativeHandler_ReplaysCachedBody) {
+  const GURL pdf_url(kOriginalUrl1);
+
   // Populate a body cache, attach it to the claimed stream, abort.
   // `TakeCachedFallbackBody` must return a valid pipe whose bytes match
   // the original body. A second take must return an invalid handle --
@@ -1309,7 +1318,7 @@
   ASSERT_TRUE(base::test::RunUntil([&] { return cache->is_complete(); }));
 
   content::RenderFrameHost* embedder_host =
-      NavigateAndCommit(main_rfh(), GURL(kOriginalUrl1));
+      NavigateAndCommit(main_rfh(), pdf_url);
   const content::FrameTreeNodeId embedder_ftn =
       embedder_host->GetFrameTreeNodeId();
   auto* manager = mime_handler_stream_manager();
@@ -1324,10 +1333,10 @@
   stream_info->SetDidExtensionFinishNavigation();
 
   manager->AbortAndFallbackToNativeHandler(embedder_host);
-  ASSERT_TRUE(manager->IsPendingNativeFallback(embedder_ftn));
+  ASSERT_TRUE(manager->IsPendingNativeFallback(embedder_ftn, pdf_url));
 
   std::optional<MimeHandlerStreamManager::CachedFallbackBody> taken =
-      manager->TakeCachedFallbackBody(embedder_ftn);
+      manager->TakeCachedFallbackBody(embedder_ftn, pdf_url);
   ASSERT_TRUE(taken.has_value());
   ASSERT_TRUE(taken->pipe.is_valid());
   EXPECT_EQ(std::string_view(kBody).size(), taken->decoded_body_size);
@@ -1338,8 +1347,71 @@
 
   // The mark stays in place until `DidFinishNavigation`/`FrameDeleted`,
   // but the body is single-use.
-  EXPECT_TRUE(manager->IsPendingNativeFallback(embedder_ftn));
-  EXPECT_FALSE(manager->TakeCachedFallbackBody(embedder_ftn).has_value());
+  EXPECT_TRUE(manager->IsPendingNativeFallback(embedder_ftn, pdf_url));
+  EXPECT_FALSE(
+      manager->TakeCachedFallbackBody(embedder_ftn, pdf_url).has_value());
+}
+
+TEST_F(MimeHandlerStreamManagerTest,
+       AbortAndFallbackToNativeHandler_RedirectedResponseUrl) {
+  const GURL pdf_url(kOriginalUrl1);
... (truncated)