gpu: Fix some context lost marking glitches+leaks and add UMA stats

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 784843737e613e7d0e3bb02a7790819a225811fb..472a9ed86c30c5a71513a203d2a7ea399e3809f5 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -11438,6 +11438,67 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   </summary>
 </histogram>
 
+<histogram name="GPU.ContextLost.BrowserCompositor" enum="ContextLostReason">

[Alexei Svitkine (slow), 2015/04/24 19:31:58]

Now that you're using this syntax, you can make this more concise, using
<histogram_suffixes> construct. See the top of the file for some documentation
and some examples within the code.

e.g. you only need on top-level <histogram entry for "GPU.ContextLost" and a
<histogram_suffixes> element that lists all the possible suffixes.

[no sievers, 2015/04/24 19:56:42]

Like this?

+  <owner>sievers@chromium.org</owner>
+  <summary>
+    The reason a BrowserCompositor GPU command buffer context was lost.
+  </summary>
+</histogram>
+
+<histogram name="GPU.ContextLost.BrowserMainThread" enum="ContextLostReason">
+  <owner>sievers@chromium.org</owner>
+  <summary>
+    The reason a BrowserMainThread GPU command buffer context was lost.
+  </summary>
+</histogram>
+
+<histogram name="GPU.ContextLost.RenderCompositor" enum="ContextLostReason">
+  <owner>sievers@chromium.org</owner>
+  <summary>
+    The reason a RenderCompositor GPU command buffer context was lost.
+  </summary>
+</histogram>
+
+<histogram name="GPU.ContextLost.RenderMainThread" enum="ContextLostReason">
+  <owner>sievers@chromium.org</owner>
+  <summary>
+    The reason a RenderMainThread GPU command buffer context was lost.
+  </summary>
+</histogram>
+
+<histogram name="GPU.ContextLost.RenderWorker" enum="ContextLostReason">
+  <owner>sievers@chromium.org</owner>
+  <summary>
+    The reason a RenderWorker GPU command buffer context was lost.
+  </summary>
+</histogram>
+
+<histogram name="GPU.ContextLost.Unknown" enum="ContextLostReason">
+  <owner>sievers@chromium.org</owner>
+  <summary>
+    The reason a GPU command buffer context of unknown type was lost.
+  </summary>
+</histogram>
+
+<histogram name="GPU.ContextLost.VideoAccelerator" enum="ContextLostReason">
+  <owner>sievers@chromium.org</owner>
+  <summary>
+    The reason a VideoAccelerator GPU command buffer context was lost.
+  </summary>
+</histogram>
+
+<histogram name="GPU.ContextLost.VideoCapture" enum="ContextLostReason">
+  <owner>sievers@chromium.org</owner>
+  <summary>
+    The reason a VideoCapture GPU command buffer context was lost.
+  </summary>
+</histogram>
+
+<histogram name="GPU.ContextLost.WebGL" enum="ContextLostReason">
+  <owner>sievers@chromium.org</owner>
+  <summary>The reason a WebGL GPU command buffer context was lost.</summary>
+</histogram>
+
 <histogram name="GPU.CreateBrowserCompositor" units="microseconds">
   <owner>vangelis@chromium.org</owner>
   <summary>
@@ -48073,6 +48134,22 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   <int value="22" label="App banner setting (Android only)"/>
 </enum>
 
+<enum name="ContextLostReason" type="int">
+  <summary>The reason for losing a GPU context.</summary>
+  <int value="0" label="CONTEXT_INIT_FAILED"/>
+  <int value="1" label="CONTEXT_LOST_GPU_CHANNEL_ERROR"/>
+  <int value="2" label="CONTEXT_PARSE_ERROR_INVALID_SIZE"/>
+  <int value="3" label="CONTEXT_PARSE_ERROR_OUT_OF_BOUNDS"/>
+  <int value="4" label="CONTEXT_PARSE_ERROR_UNKNOWN_COMMAND"/>
+  <int value="5" label="CONTEXT_PARSE_ERROR_INVALID_ARGS"/>
+  <int value="6" label="CONTEXT_PARSE_ERROR_GENERIC_ERROR"/>
+  <int value="7" label="CONTEXT_LOST_GUILTY"/>
+  <int value="8" label="CONTEXT_LOST_INNOCENT"/>
+  <int value="9" label="CONTEXT_LOST_UNKNOWN"/>
+  <int value="10" label="CONTEXT_LOST_OUT_OF_MEMORY"/>
+  <int value="11" label="CONTEXT_LOST_MAKECURRENT_FAILED"/>
+</enum>
+
 <enum name="CookieDeletionCause" type="int">
   <summary>Reason why a cookie was removed from the cookie store</summary>
   <int value="0" label="explicit">