cc: Add initial GPU-to-GPU copy rasterizer implementation.

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 9c99fb3a47da0a806b5828e14fe20df06ee416b6..2c7a09d2989013cf30c87c7aceae046ecefc09ad 100644
--- a/content/public/common/content_switches.cc
+++ b/content/public/common/content_switches.cc
@@ -319,6 +319,9 @@ const char kDisableXSLT[]                   = "disable-xslt";
 // Disables Blink's XSSAuditor. The XSSAuditor mitigates reflective XSS.
 const char kDisableXSSAuditor[]             = "disable-xss-auditor";
 
+// Disables zero-copy texture updates when using map-image based rasterizers.
+const char kDisableZeroCopy[]               = "disable-zero-copy";
+
 // Specifies if the |DOMAutomationController| needs to be bound in the
 // renderer. This binding happens on per-frame basis and hence can potentially
 // be a performance bottleneck. One should only enable it when automating dom