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

content/public/common/content_switches.cc

Index: content/public/common/content_switches.cc
diff --git a/content/public/common/content_switches.cc b/content/public/common/content_switches.cc
index c449382e5c5012492879b1220a3b131701ff60a6..087dbcf1c587a56292565b0800cb3f9330570b93 100644
--- a/content/public/common/content_switches.cc
+++ b/content/public/common/content_switches.cc
@@ -437,6 +437,11 @@ const char kEnableSkiaBenchmarking[]        = "enable-skia-benchmarking";
 // Enables slimming paint phase 2: http://www.chromium.org/blink/slimming-paint
 const char kEnableSlimmingPaintV2[]         = "enable-slimming-paint-v2";
 
+// Enables painting of Blink content from within the Blink document lifecycle
+// instead of on-request from the compositor.
+const char kEnableBlinkSynchronizedPainting[] =
+    "enable-blink-synchronized-painting";
+
 // On platforms that support it, enables smooth scroll animation.
 const char kEnableSmoothScrolling[]         = "enable-smooth-scrolling";