GitLab

When copying drawing buffer texture to canvas resource provider flip
vertically based on whether the resource provider's coordinate system
matches with the drawing buffer's.  Tested manually by simulating the
ChromeOS vertical flip state by overriding the flags in code.

Added a pixel test to simulate "save as image" functionality by using
toDataURL() which creates a snapshot of the canvas in a similar way.

Change-Id: I6e42ed6cf25ba0256294eb2859bbec8f93f94eca
Bug: 998661
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1810023Reviewed-by: Zhenyao Mo <zmo@chromium.org>
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Commit-Queue: Sunny Sachanandani <sunnyps@chromium.org>
Cr-Commit-Position: refs/heads/master@{#698719}