Add ANGLE platform methods for boolean histograms.

ui/gl/angle_platform_impl.h

Index: ui/gl/angle_platform_impl.h
diff --git a/ui/gl/angle_platform_impl.h b/ui/gl/angle_platform_impl.h
index 4f1aac4b73f125976f7d045ced179c46cd4c3db7..0549e7f511c614dd14fb0b80eb1fa0f2af371206 100644
--- a/ui/gl/angle_platform_impl.h
+++ b/ui/gl/angle_platform_impl.h
@@ -46,6 +46,7 @@ class ANGLEPlatformImpl : public angle::Platform {
                             int sample,
                             int boundary_value) override;
   void histogramSparse(const char* name, int sample) override;
+  void histogramBoolean(const char* name, bool sample) override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(ANGLEPlatformImpl);