GitLab

Update Cast API Bindings to be agnostic of MessagePort implementation
with platform-specific definitions. A common interface is exposed except
for construction, which requires different artifacts. On non-Fuchsia,
MessagePortCast still uses blink::WebMessagePort. On Fuchsia,
MessagePortFuchsia wraps fuchsia::web::MessagePort instead of requiring
an adapter to blink::WebMessagePort.

R=halliwell@chromium.org, jbroman@chromium.org, kmarshall@chromium.org

Bug: 1126571
Change-Id: Ice36b32949f45a8d1c12daa6b4a33e4b1e885a6b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2441663
Commit-Queue: Shawn Quereshi <shawnq@google.com>
Reviewed-by: Yuchen Liu <yucliu@chromium.org>
Reviewed-by: Kevin Marshall <kmarshall@chromium.org>
Reviewed-by: Jeremy Roman <jbroman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#814346}