Record task durations on Renderer Main & Compositor threads.

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 65c7eaaba6cb5723761f9a0b452aa8df1fd4dd3c..e3049cdc8d7f6122fba72be97cc40675c3b02ddd 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -67844,6 +67844,15 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <summary>How long it takes the swap ack to return after a swap.</summary>
 </histogram>
 
+<histogram name="Scheduling.TaskTime" units="microseconds">
+  <owner>tdresser@chromium.org</owner>
+  <owner>progressive-web-metrics@chromium.org</owner>
+  <summary>
+    The duration in microseconds of tasks running on the thread given by the
+    metric suffix.
+  </summary>
+</histogram>
+
 <histogram name="ScreenLocker.AuthenticationFailure" enum="UnlockType">
   <owner>sammiequon@chromium.org</owner>
   <summary>
@@ -99167,6 +99176,12 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </affected-histogram>
 </histogram_suffixes>
 
+<histogram_suffixes name="ThreadNames" separator=".">
+  <suffix name="CrRendererMain" label="The renderer main thread."/>
+  <suffix name="Compositor" label="The renderer compositor thread."/>
+  <affected-histogram name="Scheduling.TaskTime"/>
+</histogram_suffixes>
+
 <histogram_suffixes name="ThreadWatcher" separator=".">
   <suffix name="CACHE" label="where watched thread is CACHE BrowserThread."/>
   <suffix name="DB" label="where watched thread is DB BrowserThread."/>