(not for commit) Simplified multi-threaded Ganesh with lock on Flush only.

content/browser/gpu/compositor_util.h

Index: content/browser/gpu/compositor_util.h
diff --git a/content/browser/gpu/compositor_util.h b/content/browser/gpu/compositor_util.h
index 6266f36e1cbeefc7225835c72dcdef3e3f535da1..3e274be4227ca65d3ae6726999bbb94c27fa827d 100644
--- a/content/browser/gpu/compositor_util.h
+++ b/content/browser/gpu/compositor_util.h
@@ -42,6 +42,10 @@ CONTENT_EXPORT int GpuRasterizationMSAASampleCount();
 // Returns true if force-gpu-rasterization is on (via flags) for the renderer.
 CONTENT_EXPORT bool IsForceGpuRasterizationEnabled();
 
+// Returns true if disable-threaded-gpu-rasterization is off (via flags) for the
+// renderer.
+CONTENT_EXPORT bool IsThreadedGpuRasterizationEnabled();
+
 // Returns the number of raster threads to use for compositing.
 CONTENT_EXPORT int NumberOfRendererRasterThreads();