Use ScopedTaskEnvironment instead of MessageLoop in content unit tests.
ScopedTaskEnvironment allows usage of ThreadTaskRunnerHandle and
base/task_scheduler/post_task.h within its scope. It should be
instantiated in every unit test that uses either of these APIs
(i.e. no test should instantiate a MessageLoop directly).
Motivation for ScopedTaskEnvironment can be found in:
https://docs.google.com/document/d/1QabRo8c7D9LsYY3cEcaPQbOCLo8Tu-6VLykYXyl3Pkk/edit
BUG=708584
R=gab@chromium.org
TBR=michaeln@chromium.org, aelias@chromium.org, yfriedman@chromium.org
Review-Url: https://codereview.chromium.org/2800893002
Cr-Commit-Position: refs/heads/master@{#462528}
24 files changed
