BTW, if you look into this code, I think there might be an issue with the UMA we record for headset: we might be recording all the time, even if it's not actually used for play/pause.

Thanks, I was wondering why HeadsetUnplug is the majority for MediaSession.Suspend. This should be the cause.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/e03e8ee0fc359e38700001f04b7ec2e9a01f5f52

commit e03e8ee0fc359e38700001f04b7ec2e9a01f5f52
Author: zqzhang <zqzhang@chromium.org>
Date: Thu Aug 18 15:01:21 2016

Fixing headset unplug issues in MediaNotification

This CL make MediaNotification fire a ACTION_STOP PendingIntent when the
notification is dismissed, making the MediaSession inactive.

Also, MediaNotification will not call play()/pause() when the
notification is already in that state, preventing calling pause() when
unpluging headset when the notification is already in paused state.

An unplug-related UMA issue is also fixed in this CL.

BUG= 638858 

Review-Url: https://codereview.chromium.org/2253293004
Cr-Commit-Position: refs/heads/master@{#412829}

[modify] https://crrev.com/e03e8ee0fc359e38700001f04b7ec2e9a01f5f52/chrome/android/java/src/org/chromium/chrome/browser/media/ui/MediaNotificationManager.java

Requesting to merge in M53 since this is a regression since M52

Your change meets the bar and is auto-approved for M53 (branch: 2785)

Manually post the merge message:

Patchset landed as:

https://chromium.googlesource.com/chromium/src.git/+/9362f358fd3f2456a71547e54bf4bafbc803246f

Description

Fixing headset unplug issues in MediaNotification

This CL make MediaNotification fire a ACTION_STOP PendingIntent when the
notification is dismissed, making the MediaSession inactive.

Also, MediaNotification will not call play()/pause() when the
notification is already in that state, preventing calling pause() when
unpluging headset when the notification is already in paused state.

An unplug-related UMA issue is also fixed in this CL.

BUG= 638858 

Review-Url: https://codereview.chromium.org/2253293004
Cr-Commit-Position: refs/heads/master@{#412829}
(cherry picked from commit e03e8ee0fc359e38700001f04b7ec2e9a01f5f52)

Review URL: https://codereview.chromium.org/2260563002 .

This issue has been approved for a merge. Please merge the fix to any appropriate branches as soon as possible!

If all merges have been completed, please remove any remaining Merge-Approved labels from this issue.

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

The patch has already landed on 2785.
Posting land message and change the merge-* tag

Fixing headset unplug issues in MediaNotification

This CL make MediaNotification fire a ACTION_STOP PendingIntent when the
notification is dismissed, making the MediaSession inactive.

Also, MediaNotification will not call play()/pause() when the
notification is already in that state, preventing calling pause() when
unpluging headset when the notification is already in paused state.

An unplug-related UMA issue is also fixed in this CL.

BUG= 638858 

Review-Url: https://codereview.chromium.org/2253293004
Cr-Commit-Position: refs/heads/master@{#412829}
(cherry picked from commit e03e8ee0fc359e38700001f04b7ec2e9a01f5f52)

Review URL: https://codereview.chromium.org/2260563002 .

Cr-Commit-Position: refs/branch-heads/2785@{#657}
Cr-Branched-From: 68623971be0cfc492a2cb0427d7f478e7b214c24-refs/heads/master@{#403382}