We now observe the message loop and the mojo message pump directly.

R=ojan@chromium.org, eseidel@chromium.org

Review URL: https://codereview.chromium.org/673783006

Previously, Canvas2DLayerManager was using addTaskObserver to jump the task
queue. After this CL, it goes to the end of the queue like a normal task.

R=ojan@chromium.org

Review URL: https://codereview.chromium.org/673783005

R=abarth@chromium.org

Review URL: https://codereview.chromium.org/645513006

R=abarth@chromium.org

Review URL: https://codereview.chromium.org/672323002

R=eseidel@chromium.org

Review URL: https://codereview.chromium.org/677513002

Turns out our shut-down code in debugger.cc is never
called.  Need to talk to Ben to figure out how
to listen for the CloseWindow.

R=abarth@chromium.org

Review URL: https://codereview.chromium.org/658113004

R=abarth@chromium.org

Review URL: https://codereview.chromium.org/671173004

Sky uses Mojo services to communicate between embedded applications, not
postMessage and its friends.

R=abarth@chromium.org

Review URL: https://codereview.chromium.org/676723003

We don't enable this runtime setting.

R=ojan@google.com, ojan@chromium.org

Review URL: https://codereview.chromium.org/678483002

R=esprehn@chromium.org

Review URL: https://codereview.chromium.org/671633005

TBR=eseidel@chromium.org

Review URL: https://codereview.chromium.org/677483002

R=esprehn@chromium.org

Review URL: https://codereview.chromium.org/657863003

R=jamesr@chromium.org

Review URL: https://codereview.chromium.org/672963002