M63 Stable promotion is coming soon and your bug is labelled as Stable ReleaseBlock, pls make sure to land the fix and request a merge to M63 ASAP. Thank you.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/3defa5495fc19bb5115286876dc94e0887874cd2

commit 3defa5495fc19bb5115286876dc94e0887874cd2
Author: Dale Curtis <dalecurtis@chromium.org>
Date: Tue Nov 07 00:52:32 2017

Fix hung streams if a track change never reaches have_enough.

During a track change it's possible that a renderer will never
reach the have_enough state again. I.e., with MSE a client may
want to seek to a later location. The current code means the
renderer will get stuck forever waiting for data that never
comes.

Instead Flush() calls from the Pipeline should always take
precedence and cancel any track changes in progress. Upstream
of the renderer the demuxer has already had the track enabled,
so just letting the normal Flush() process occur is sufficient
to restart the track.

BUG= 781010 
TEST=updated unittest

Change-Id: I5c005e728d9c1babf2a95c2e603a75f7976ec16d
Reviewed-on: https://chromium-review.googlesource.com/752048
Commit-Queue: Dale Curtis <dalecurtis@chromium.org>
Reviewed-by: Sergey Volk <servolk@chromium.org>
Reviewed-by: Xiaohan Wang <xhwang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#514324}
[modify] https://crrev.com/3defa5495fc19bb5115286876dc94e0887874cd2/media/renderers/renderer_impl.cc
[modify] https://crrev.com/3defa5495fc19bb5115286876dc94e0887874cd2/media/renderers/renderer_impl.h
[modify] https://crrev.com/3defa5495fc19bb5115286876dc94e0887874cd2/media/renderers/renderer_impl_unittest.cc

Looks good on canary and user confirms fix.

This bug requires manual review: M63 has already been promoted to the beta branch, so this requires manual review
Please contact the milestone owner if you have questions.
Owners: cmasso@(Android), cmasso@(iOS), gkihumba@(ChromeOS), govind@(Desktop)

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

Approving merge to M63 branch 3239 based on comment #3 and per offline chat with  dalecurtis@. 

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/3eac11068c80b99e2f5304ae40d5e8e4ce65d1ea

commit 3eac11068c80b99e2f5304ae40d5e8e4ce65d1ea
Author: Dale Curtis <dalecurtis@chromium.org>
Date: Wed Nov 08 23:50:48 2017

Merge M63: "Fix hung streams if a track change never reaches have_enough."

During a track change it's possible that a renderer will never
reach the have_enough state again. I.e., with MSE a client may
want to seek to a later location. The current code means the
renderer will get stuck forever waiting for data that never
comes.

Instead Flush() calls from the Pipeline should always take
precedence and cancel any track changes in progress. Upstream
of the renderer the demuxer has already had the track enabled,
so just letting the normal Flush() process occur is sufficient
to restart the track.

BUG= 781010 
TEST=updated unittest
TBR=dalecurtis@chromium.org, xhwang

(cherry picked from commit 3defa5495fc19bb5115286876dc94e0887874cd2)

Change-Id: I5c005e728d9c1babf2a95c2e603a75f7976ec16d
Reviewed-on: https://chromium-review.googlesource.com/752048
Commit-Queue: Dale Curtis <dalecurtis@chromium.org>
Reviewed-by: Sergey Volk <servolk@chromium.org>
Reviewed-by: Xiaohan Wang <xhwang@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#514324}
Reviewed-on: https://chromium-review.googlesource.com/758967
Reviewed-by: Dale Curtis <dalecurtis@chromium.org>
Cr-Commit-Position: refs/branch-heads/3239@{#425}
Cr-Branched-From: adb61db19020ed8ecee5e91b1a0ea4c924ae2988-refs/heads/master@{#508578}
[modify] https://crrev.com/3eac11068c80b99e2f5304ae40d5e8e4ce65d1ea/media/renderers/renderer_impl.cc
[modify] https://crrev.com/3eac11068c80b99e2f5304ae40d5e8e4ce65d1ea/media/renderers/renderer_impl.h
[modify] https://crrev.com/3eac11068c80b99e2f5304ae40d5e8e4ce65d1ea/media/renderers/renderer_impl_unittest.cc