compositor: Disable partial raster by default.

content/browser/gpu/compositor_util.cc

Index: content/browser/gpu/compositor_util.cc
diff --git a/content/browser/gpu/compositor_util.cc b/content/browser/gpu/compositor_util.cc
index eb2d69b81af3be49e61bdf332aa2a4528ce8cb44..da391747a434c38f94e6fa487a893725753ab907 100644
--- a/content/browser/gpu/compositor_util.cc
+++ b/content/browser/gpu/compositor_util.cc
@@ -219,8 +219,9 @@ bool IsPartialRasterEnabled() {
   // Zero copy currently doesn't take advantage of partial raster.
   if (IsZeroCopyUploadEnabled())
     return false;
-  const auto& command_line = *base::CommandLine::ForCurrentProcess();
-  return !command_line.HasSwitch(switches::kDisablePartialRaster);
+
+  // TODO(dshwang): enable partial raster. crbug.com/492754
+  return false;
 }
 
 bool IsGpuMemoryBufferCompositorResourcesEnabled() {