Add an histogram to differentiate between hang types of the renderer

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 84a0cddca55924ed6434d98513875a9781327b4a..3722e362c7b75cef72426f698683ccd891bfcfc0 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -5042,6 +5042,14 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="ChildProcess.HangRendererType" enum="RendererUnresponsiveType">
+  <owner>clamy@chromium.org</owner>
+  <summary>
+    What the browser was waiting for from the renderer when it was reported as
+    hung.
+  </summary>
+</histogram>
+
 <histogram name="ChildProcess.InvalidSandboxStateCrash.NoStartupWindow"
     enum="BooleanPresent">
   <owner>wfh@chromium.org</owner>
@@ -88080,6 +88088,16 @@ To add a new entry, add it with any value and run test to compute valid value.
   <int value="2" label="Extension renderer"/>
 </enum>
 
+<enum name="RendererUnresponsiveType" type="int">
+  <int value="0" label="Unknown"/>
+  <int value="1" label="Pending in-flight events"/>
+  <int value="2" label="Waiting for dialog closed"/>
+  <int value="3" label="Suppressed dialogs in unload events"/>
+  <int value="4" label="During BeforeUnload"/>
+  <int value="5" label="During Unload"/>
+  <int value="6" label="While closing the page"/>
+</enum>
+
 <enum name="RenderViewContextMenuItem" type="int">
   <int value="0" label="IDC_CONTENT_CONTEXT_CUSTOM_FIRST"/>
   <int value="1" label="IDC_EXTENSIONS_CONTEXT_CUSTOM_FIRST"/>