[Android] Add support for a hung renderer dialog

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 515673243075ffe73d19964f2caf110b36fd3eee..967cf2c187f4f8a863903252e674e024356eee1a 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -14463,6 +14463,17 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <summary>The type of Vary header for a given GET response.</summary>
 </histogram>
 
+<histogram name="HungRenderer.MobileInfoBar.Event"

[Alexei Svitkine (slow), 2015/09/02 15:26:10]

Nit: This is adding a new top-level prefix. Unless you're planning to add many
histograms with this prefix, I suggest finding an existing prefix to nest this
under.

e.g. "Renderer.Hung.MobileInfoBar.UserEvent".

[jdduke (slow), 2015/09/02 16:56:07]

Done.

+    enum="MobileHungRendererInfoBarEvent">
+  <owner>jdduke@chromium.org</owner>
+  <summary>
+    Android: Records the terminal event associated with a hung renderer infobar.
+    This includes both the explicit user actions as well as implicit dismissals,
+    e.g., when the renderer regains responsiveness before the infobar is
+    interactively dismissed.
+  </summary>
+</histogram>
+
 <histogram name="Import.ImporterType.AutoImport" enum="ImporterType">
   <owner>gab@chromium.org</owner>
   <summary>The importer used on first run Auto Import.</summary>
@@ -65078,6 +65089,14 @@ To add a new entry, add it with any value and run test to compute valid value.
   <int value="4" label="No thanks"/>
 </enum>
 
+<enum name="MobileHungRendererInfoBarEvent" type="int">
+  <int value="0" label="Clicked the 'Wait' button"/>
+  <int value="1" label="Clicked the 'Kill' button"/>
+  <int value="2" label="Clicked the 'X' (close) button)"/>
+  <int value="3" label="Infobar dismissed after renderer became responsive"/>
+  <int value="4" label="Infobar dismissed on shutdown"/>
+</enum>
+
 <enum name="MobileSessionShutdownType" type="int">
   <int value="0" label="Shutdown in background"/>
   <int value="1" label="Shutdown in foreground; no log; no memory warning"/>