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

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 1dc495a7758c04c69d997db43cfdcd42202a7835..fe5e2abdcc6596eacefab71430311e026c717dc9 100644
--- a/content/browser/gpu/compositor_util.h
+++ b/content/browser/gpu/compositor_util.h
@@ -17,6 +17,8 @@ namespace content {
 // default).
 CONTENT_EXPORT bool IsPropertyTreeVerificationEnabled();
 
+CONTENT_EXPORT bool IsBlinkSynchronizedPaintingEnabled();
+
 // Returns true if zero-copy uploads is on (via flags, or platform default).
 // Only one of one-copy and zero-copy can be enabled at a time.
 CONTENT_EXPORT bool IsZeroCopyUploadEnabled();