Blink MediaRecorder: adding "creation" LayoutTest and reconnecting "canRecordMimeType"

This CL:
- reconnects canRecordMimeType LayoutTest
- adds a new -creation test
- _does not_ reconnect basic-video test because the
underlying Cr test infra does not provide meaningful
video tracks, hitting a DCHECK in VideoTrackRecorder
(I need to work on that).
- changes a ASSERT_NOTREACHED() in MediaRecorder
with a WTF_LOG() to allow debugging.
- Allows writeData() to be called when MediaRecorder 
is not in Recording state if |lastInSlice| is true.

BUG=262211

Review URL: https://codereview.chromium.org/1336943004

git-svn-id: svn://svn.chromium.org/blink/trunk@202376 bbb929c8-8fbe-4397-9dbb-9b2b20218538
5 files changed
tree: cf7d5655565b92ef00dea9c8516df6651191005f
  1. third_party/