Turn off computation of the interest rect in cc in synchronized paint mode.

content/browser/renderer_host/render_view_host_impl.cc

Index: content/browser/renderer_host/render_view_host_impl.cc
diff --git a/content/browser/renderer_host/render_view_host_impl.cc b/content/browser/renderer_host/render_view_host_impl.cc
index a3dcee9c9222f5980815b749fcf294f81ba7c053..3a0b50ab3a39025da65f0948cf69fd8eae990e76 100644
--- a/content/browser/renderer_host/render_view_host_impl.cc
+++ b/content/browser/renderer_host/render_view_host_impl.cc
@@ -485,6 +485,9 @@ WebPreferences RenderViewHostImpl::ComputeWebkitPrefs() {
   prefs.slimming_paint_v2_enabled =
       command_line.HasSwitch(switches::kEnableSlimmingPaintV2);
 
+  prefs.blink_synchronized_painting_enabled =
+      command_line.HasSwitch(switches::kEnableBlinkSynchronizedPainting);
+
 #if defined(OS_MACOSX) || defined(OS_CHROMEOS)
   bool default_enable_scroll_animator = true;
 #else