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 9e5d4024997134f9bbe92333ee957a1449686209..ed042186ccf781b869c658bee3824acbe8931730 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -11410,6 +11410,16 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   </summary>
 </histogram>
 
+<histogram name="GPU.BrowserCompositorContextLost" enum="ContextLostReason">
+  <owner>sievers@chromium.org</owner>
+  <summary>The reason a GPU command buffer context was lost.</summary>
+</histogram>
+
+<histogram name="GPU.BrowserMainThreadContextLost" enum="ContextLostReason">
+  <owner>sievers@chromium.org</owner>
+  <summary>The reason a GPU command buffer context was lost.</summary>
+</histogram>
+
 <histogram name="GPU.CollectContextGraphicsInfo" units="microseconds">
   <owner>vangelis@chromium.org</owner>
   <summary>
@@ -11463,6 +11473,21 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   </summary>
 </histogram>
 
+<histogram name="GPU.RenderCompositorContextLost" enum="ContextLostReason">
+  <owner>sievers@chromium.org</owner>
+  <summary>The reason a GPU command buffer context was lost.</summary>
+</histogram>
+
+<histogram name="GPU.RenderMainThreadContextLost" enum="ContextLostReason">
+  <owner>sievers@chromium.org</owner>
+  <summary>The reason a GPU command buffer context was lost.</summary>
+</histogram>
+
+<histogram name="GPU.RenderWorkerContextLost" enum="ContextLostReason">
+  <owner>sievers@chromium.org</owner>
+  <summary>The reason a GPU command buffer context was lost.</summary>
+</histogram>
+
 <histogram name="GPU.TextureRG" enum="BooleanAvailable">
   <owner>reveman@chromium.org</owner>
   <summary>
@@ -11471,6 +11496,26 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   </summary>
 </histogram>
 
+<histogram name="GPU.UnknownContextTypeLost" enum="ContextLostReason">
+  <owner>sievers@chromium.org</owner>
+  <summary>The reason a GPU command buffer context was lost.</summary>
+</histogram>
+
+<histogram name="GPU.VideoAcceleratorContextLost" enum="ContextLostReason">
+  <owner>sievers@chromium.org</owner>
+  <summary>The reason a GPU command buffer context was lost.</summary>
+</histogram>
+
+<histogram name="GPU.VideoCaptureContextLost" enum="ContextLostReason">
+  <owner>sievers@chromium.org</owner>
+  <summary>The reason a GPU command buffer context was lost.</summary>
+</histogram>
+
+<histogram name="GPU.WebGLContextLost" enum="ContextLostReason">
+  <owner>sievers@chromium.org</owner>
+  <summary>The reason a GPU command buffer context was lost.</summary>
+</histogram>
+
 <histogram name="Hardware.Display.Count.OnChange">
   <owner>erikchen@chromium.org</owner>
   <summary>
@@ -47693,6 +47738,22 @@ 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">