Complete the plumbing of CanvasResource through CanvasResourceDispatcher

This CL completes the the last link of plumbing allowing CanvasResource
objects of any type to be pushed all the way through to the compositor.

BUG=788439
TBR=fserb@chromium.org

Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_layout_tests_slimming_paint_v2;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: I08c9775b0e62e5dd7fd3a9cb73d0b6dba0e43ccc
Reviewed-on: https://chromium-review.googlesource.com/1144602
Commit-Queue: Justin Novosad <junov@chromium.org>
Reviewed-by: Justin Novosad <junov@chromium.org>
Cr-Commit-Position: refs/heads/master@{#576882}
8 files changed