Add runtime flag to enable the display list 2D canvas 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 c9097e6f89eaa661100a0573414aa4ebc8a7e229..db429e3c852ccc9ae72d6daf97159eef34415154 100644
--- a/content/public/common/content_switches.cc
+++ b/content/public/common/content_switches.cc
@@ -349,6 +349,9 @@ const char kEnableDeferredImageDecoding[]   = "enable-deferred-image-decoding";
 // Enables delegated renderer.
 const char kEnableDelegatedRenderer[]       = "enable-delegated-renderer";
 
+// Enables display list based 2d canvas implementation.
+const char kEnableDisplayList2dCanvas[]     = "enable-display-list-2d-canvas";
+
 // Enables restarting interrupted downloads.
 const char kEnableDownloadResumption[]      = "enable-download-resumption";