Add flag to disable impl-side painting

chrome/app/generated_resources.grd

Index: chrome/app/generated_resources.grd
diff --git a/chrome/app/generated_resources.grd b/chrome/app/generated_resources.grd
index dfe0631bac468052c7443e4fa140b5d7a3766567..0023b8f26c2dac4760b3599bd043e9a519e8e667 100644
--- a/chrome/app/generated_resources.grd
+++ b/chrome/app/generated_resources.grd
@@ -7162,6 +7162,12 @@ Keep your key file in a safe place. You will need it to create new versions of y
           <!-- TODO Add description of enable SPDY proxy flag. -->
         </message>
       </if>
+      <message name="IDS_FLAGS_IMPL_SIDE_PAINTING_NAME" desc="Name of about:flags option for impl-side painting.">
+        Impl-side painting
+      </message>
+      <message name="IDS_FLAGS_IMPL_SIDE_PAINTING_DESCRIPTION" desc="Description of about:flags option for impl-side painting.">
+        If enabled, painting is done on a separate thread instead of the main thread.
+      </message>
 
       <!-- Crashes -->
       <message name="IDS_CRASHES_TITLE" desc="Title for the chrome://crashes page.">