Add fixed raster scale use counter histograms.

blimp/client/feature/compositor/blimp_compositor.h

Index: blimp/client/feature/compositor/blimp_compositor.h
diff --git a/blimp/client/feature/compositor/blimp_compositor.h b/blimp/client/feature/compositor/blimp_compositor.h
index df39b0f02aeb42bfe773f6f1899fbd2df328c00e..3836f4a3e1449c60a8c772f33c9535b2071534f5 100644
--- a/blimp/client/feature/compositor/blimp_compositor.h
+++ b/blimp/client/feature/compositor/blimp_compositor.h
@@ -149,6 +149,9 @@ class BlimpCompositor
   void DidCommitAndDrawFrame() override;
   void DidCompleteSwapBuffers() override;
   void DidCompletePageScaleAnimation() override;
+  void ReportFixedRasterScaleUseCounters(

[chrishtr, 2016/05/05 20:33:07]

I guess you already implemented it, but maybe overkill to support Blimp for
this?

[vmpstr, 2016/05/06 19:53:48]

It's just an empty implementation since the interface not requires it. 

+      bool has_blurry_content,
+      bool has_potential_performance_regression) override {}
 
   // RemoteProtoChannel implementation.
   void SetProtoReceiver(ProtoReceiver* receiver) override;