Stop exposing --disable-gpu-compositing as a Blink RuntimeEnabledFeature

content/renderer/renderer_blink_platform_impl.h

Index: content/renderer/renderer_blink_platform_impl.h
diff --git a/content/renderer/renderer_blink_platform_impl.h b/content/renderer/renderer_blink_platform_impl.h
index 309259a3df2c1e8757523df7c641435f7fe59b8f..f3f64bcf2b9c2f895e91b8b4d44a3a2f12a89c91 100644
--- a/content/renderer/renderer_blink_platform_impl.h
+++ b/content/renderer/renderer_blink_platform_impl.h
@@ -142,6 +142,7 @@ class CONTENT_EXPORT RendererBlinkPlatformImpl : public BlinkPlatformImpl {
 
   bool isThreadedCompositingEnabled() override;
   bool isThreadedAnimationEnabled() override;
+  bool isGPUCompositingEnabled() override;
   double audioHardwareSampleRate() override;
   size_t audioHardwareBufferSize() override;
   unsigned audioHardwareOutputChannels() override;