[TO 56] Fix race in media Pipeline::GetMediaTime() after seeking.

[TO 56] Fix race in media Pipeline::GetMediaTime() after seeking.

Seeking posts a task from main thread to media thread to seek the
renderer. Calling GetMediaTime() should be safe even when the
renderer has not yet received the message to performed the seek.

This change gaurds against using the renderer's media time while
a seek is pending. This prevents polluting |last_media_time_|
with bad values from the renderer that doesn't yet know about
the seek.

BUG=675556
TEST=New unit test && manually verfied bug fix.
TBR=sandersd@chromium.org

Review-Url: https://codereview.chromium.org/2616703002
Cr-Commit-Position: refs/heads/master@{#441526}
(cherry picked from commit 454da202ef172f3ecbfb48c154ff97c8c10011b0)

Review-Url: https://codereview.chromium.org/2621183002 .
Cr-Commit-Position: refs/branch-heads/2924@{#722}
Cr-Branched-From: 3a87aecc31cd1ffe751dd72c04e5a96a1fc8108a-refs/heads/master@{#433059}
Committed: https://chromium.googlesource.com/chromium/src/+/f683e0741087dbe0ddf4ed5d878bc72b61246ff8

[chcunningham, 2017-01-10 22:04:06]

Description was changed from

==========
[TO 56] Fix race in media Pipeline::GetMediaTime() after seeking.

Seeking posts a task from main thread to media thread to seek the
renderer. Calling GetMediaTime() should be safe even when the
renderer has not yet received the message to performed the seek.

This change gaurds against using the renderer's media time while
a seek is pending. This prevents polluting |last_media_time_|
with bad values from the renderer that doesn't yet know about
the seek.

BUG=675556
TEST=New unit test && manually verfied bug fix.
TBR=sandersd@chromium.org

Review-Url: https://codereview.chromium.org/2616703002
Cr-Commit-Position: refs/heads/master@{#441526}
(cherry picked from commit 454da202ef172f3ecbfb48c154ff97c8c10011b0)
==========

to

==========
[TO 56] Fix race in media Pipeline::GetMediaTime() after seeking.

Seeking posts a task from main thread to media thread to seek the
renderer. Calling GetMediaTime() should be safe even when the
renderer has not yet received the message to performed the seek.

This change gaurds against using the renderer's media time while
a seek is pending. This prevents polluting |last_media_time_|
with bad values from the renderer that doesn't yet know about
the seek.

BUG=675556
TEST=New unit test && manually verfied bug fix.
TBR=sandersd@chromium.org

Review-Url: https://codereview.chromium.org/2616703002
Cr-Commit-Position: refs/heads/master@{#441526}
(cherry picked from commit 454da202ef172f3ecbfb48c154ff97c8c10011b0)

Review-Url: https://codereview.chromium.org/2621183002 .
Cr-Commit-Position: refs/branch-heads/2924@{#722}
Cr-Branched-From:
3a87aecc31cd1ffe751dd72c04e5a96a1fc8108a-refs/heads/master@{#433059}
Committed:
https://chromium.googlesource.com/chromium/src/+/f683e0741087dbe0ddf4ed5d878b...
==========

[chcunningham, 2017-01-10 22:04:08]

Committed patchset #1 (id:1) manually as
f683e0741087dbe0ddf4ed5d878bc72b61246ff8 (presubmit successful).