Include compositing reasons in the "debug" GraphicsLayer tree dump.
Include compositing reasons in the "debug" GraphicsLayer tree dump.

It's useful.

R=hartmanng@chromium.org
BUG=None

Review URL: https://codereview.chromium.org/176963018

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@168489 bbb929c8-8fbe-4397-9dbb-9b2b20218538

primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs