Pass invalidationReason annotation by tracing JSON

This CL modifies the way invalidation rect is annotated for debug purposes.

r181774 introduced getAnnotatedInvalidationRects to expose Blink embedder
detailed information about GraphicsLayer invalidations.

This CL replaces the API introduced in r181774 and includes the information
in GraphicsLayerDebugInfo JSON output.

In this way, we can pass the information directly to FrameViewer without
proxying it in cc.

BUG=402033

Review URL: https://codereview.chromium.org/617723002

git-svn-id: svn://svn.chromium.org/blink/trunk@183033 bbb929c8-8fbe-4397-9dbb-9b2b20218538