Shape Detection: initialize all mojo::Bitmap fields

This CL initializes all the fields of the newly allocated
skia::mojom::blink::Bitmap before sending it over mojo,
otherwise I get

[...:ERROR:validation_errors.cc(87)] Invalid message: VALIDATION_ERROR_DESERIALIZATION_FAILED

when running a Chromium build with the demos
- https://codepen.io/miguelao/full/ygxVqg
- https://codepen.io/miguelao/full/wgrYjZ
- https://codepen.io/miguelao/full/ORYbbm

Interestingly, content_browsertests are passing both
in the bots and locally.  Perhaps a different deserialization
validation logic is used in different cases?

BUG=665488
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.mac:mac_optional_gpu_tests_rel

Review-Url: https://codereview.chromium.org/2771703002
Cr-Commit-Position: refs/heads/master@{#458960}
1 file changed