cc: Enable renderer compositor impl-side painting on Mac.

TBR=piman@chromium.org
BUG=169282

Review URL: https://codereview.chromium.org/501913002

Cr-Commit-Position: refs/heads/master@{#291721}

content/browser/gpu/compositor_util.cc

@@ -197,11 +197,7 @@ bool IsImplSidePaintingEnabled() {
       switches::kEnableBleedingEdgeRenderingFastPaths))
     return true;
 
-#if defined(OS_MACOSX)
-  return false;
-#else
   return true;
-#endif
 }
 
 bool IsGpuRasterizationEnabled() {