From 3431f8c719ae078361e10e6afa9d2f0c933a6cce Mon Sep 17 00:00:00 2001
From: Danil Somsikov <dsv@chromium.org>
Date: Thu, 16 Jul 2026 09:52:06 -0700
Subject: [PATCH] Add UMA histogram for DevTools frontend location.

This CL introduces a new UMA histogram, DevTools.FrontendLocation, to record whether the DevTools frontend is loaded from a local source (e.g., bundled with Chrome or a custom local build) or a remote source (e.g., served from a CDN). This metric is recorded once per DevTools session at the start.

Bug: 520492291
Change-Id: Icefc85c70d7407a15d2a9004ad64ab32802bddbd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/8106695
Reviewed-by: Alex Rudenko <alexrudenko@chromium.org>
Auto-Submit: Danil Somsikov <dsv@chromium.org>
Commit-Queue: Danil Somsikov <dsv@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1663215}
---

diff --git a/chrome/browser/devtools/devtools_ui_bindings.cc b/chrome/browser/devtools/devtools_ui_bindings.cc
index 49472ab..b431b7e 100644
--- a/chrome/browser/devtools/devtools_ui_bindings.cc
+++ b/chrome/browser/devtools/devtools_ui_bindings.cc
@@ -549,6 +549,12 @@
                              base::Value(encoded));
 }
 
+enum class DevToolsFrontendLocation {
+  kLocal = 0,
+  kRemote = 1,
+  kMaxValue = kRemote,
+};
+
 bool IsLocalDevToolsFrontendURL(const GURL& url) {
   if (!url.is_valid() || url.IsAboutBlank() ||
       !url.SchemeIs(content::kChromeDevToolsScheme) ||
@@ -2462,6 +2468,14 @@
     if (!remote_debugging_enabled) {
       session_tags |= SessionTags::kDevToolsRemoteDebuggingDisabled;
     }
+
+    // Log the frontend location explicitly
+    GURL frontend_url = web_contents_->GetVisibleURL();
+    DevToolsFrontendLocation location = IsLocalDevToolsFrontendURL(frontend_url)
+                                            ? DevToolsFrontendLocation::kLocal
+                                            : DevToolsFrontendLocation::kRemote;
+    base::UmaHistogramEnumeration("DevTools.FrontendLocation", location);
+
     metrics::structured::StructuredMetricsClient::Record(
         metrics::structured::events::v2::dev_tools::SessionStart()
             .SetTags(session_tags)
diff --git a/tools/metrics/histograms/metadata/dev/enums.xml b/tools/metrics/histograms/metadata/dev/enums.xml
index 7fc33db1..0f8bd1b7 100644
--- a/tools/metrics/histograms/metadata/dev/enums.xml
+++ b/tools/metrics/histograms/metadata/dev/enums.xml
@@ -1012,6 +1012,11 @@
   <int value="2" label="Other Extension"/>
 </enum>
 
+<enum name="DevToolsFrontendLocation">
+  <int value="0" label="Local"/>
+  <int value="1" label="Remote"/>
+</enum>
+
 <enum name="DevToolsIssueCreated">
   <int value="0" label="MixedContentIssue"/>
   <int value="1" label="ContentSecurityPolicyIssue::kInlineViolation"/>
diff --git a/tools/metrics/histograms/metadata/dev/histograms.xml b/tools/metrics/histograms/metadata/dev/histograms.xml
index 529c9ef..617578bf 100644
--- a/tools/metrics/histograms/metadata/dev/histograms.xml
+++ b/tools/metrics/histograms/metadata/dev/histograms.xml
@@ -185,6 +185,17 @@
   </summary>
 </histogram>
 
+<histogram name="DevTools.FrontendLocation" enum="DevToolsFrontendLocation"
+    expires_after="2027-01-16">
+  <owner>dsv@chromium.org</owner>
+  <owner>chrome-devtools@google.com</owner>
+  <summary>
+    Records whether the DevTools frontend being loaded is local (bundled/custom)
+    or remote (served via CDN). Recorded once per DevTools session at session
+    start.
+  </summary>
+</histogram>
+
 <histogram name="DevTools.Insights.LongTeaserGenerationTime" units="ms"
     expires_after="2026-10-24">
   <owner>wolfi@google.com</owner>