tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index 22aa63fd7b1a2163fab7c977e309f75639e3e6fb..fcd40c2698cdc36c1c4e7b727b0d7d61da6c8424 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -18599,7 +18599,8 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 <histogram name="Extensions.InjectEnd_Time" units="ms">
   <owner>rdevlin.cronin@chromium.org</owner>
   <summary>
-    Time taken to inject all scripts at document end by extensions.
+    Time taken to inject all scripts at document end by extensions. Not reported

[Devlin, 2017/03/22 13:56:06]

Is this correct?  I thought the histogram would still be emitted, but would only
account for the synchronous injection time.  If that's the case, maybe something
like:
// Synchronous time taken to inject all scripts at document end by extensions. 
If
// scripts are injected asynchronously, this does not include the total time for
// the script to run.  Usually, prefer Extensions.InjectedScriptExecutionTime.

[Kunihiko Sakamoto, 2017/03/23 06:45:31]

This is correct (I checked locally) -- asynchronous injections are counted as
|num_blocking_js| in ScriptsRunInfo, and that prevents this histogram from being
logged.

https://cs.chromium.org/chromium/src/extensions/renderer/scripts_run_info.cc?...

+    if scripts are executed asynchronously.
   </summary>
 </histogram>
 
@@ -18618,7 +18619,8 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 <histogram name="Extensions.InjectIdle_Time" units="ms">
   <owner>rdevlin.cronin@chromium.org</owner>
   <summary>
-    Time taken to inject all scripts at document idle by extensions.
+    Time taken to inject all scripts at document idle by extensions. Not
+    reported if scripts are executed asynchronously.
   </summary>
 </histogram>
 
@@ -18650,7 +18652,8 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 <histogram name="Extensions.InjectStart_Time" units="ms">
   <owner>rdevlin.cronin@chromium.org</owner>
   <summary>
-    Time taken to inject css/scripts at document start by extensions.
+    Time taken to inject css/scripts at document start by extensions. Not
+    reported if scripts are executed asynchronously.
   </summary>
 </histogram>
 
@@ -123120,6 +123123,13 @@ from previous Chrome versions.
   <affected-histogram name="Setup.Install.LzmaUnPackStatus"/>
 </histogram_suffixes>
 
+<histogram_suffixes name="UserScriptRunLocation" separator=".">
+  <suffix name="DocumentStart"/>
+  <suffix name="DocumentEnd"/>
+  <suffix name="DocumentIdle"/>

[Ilya Sherman, 2017/03/22 22:38:06]

nit: Please add a brief label for each suffix.

[Kunihiko Sakamoto, 2017/03/23 06:45:31]

Done.

+  <affected-histogram name="Extensions.InjectedScriptExecutionTime"/>
+</histogram_suffixes>
+
 <histogram_suffixes name="V8SpecialApps" separator=".">
   <suffix name="calendar" label="Custom histogram for Calendar"/>
   <suffix name="docs" label="Custom histogram for Google Docs and Drive"/>