WebView: enable cc::switches::kCheckDamageEarly

Allow webview to check damage in OnBeginFrame to prevent
unnecessary draws.


Change-Id: I45269b7ae6223358b756c523197b309d7bc5155e
Reviewed-on: https://chromium-review.googlesource.com/868503Reviewed-by: Bo <boliu@chromium.org>
Commit-Queue: James Wallace-Lee <jamwalla@chromium.org>
Cr-Commit-Position: refs/heads/master@{#537922}

android_webview/lib/aw_main_delegate.cc

@@ -81,6 +81,9 @@ bool AwMainDelegate::BasicStartupComplete(int* exit_code) {
   cl->AppendSwitch(switches::kDisableWebRtcHWDecoding);
 #endif
 
+  // Check damage in OnBeginFrame to prevent unnecessary draws.
+  cl->AppendSwitch(cc::switches::kCheckDamageEarly);
+
   // This is needed for sharing textures across the different GL threads.
   cl->AppendSwitch(switches::kEnableThreadedTextureMailboxes);