Fix an issue that download progress notification is shown when killing browser

Fix an issue that download progress notification is shown when killing browser

When browser gets killed, we should show a paused notification.
However, onTaskRemoved() is often called too early before process fully
stops.
As a result, a progress notification can arrive after Chrome changes all the
notification to paused.
This may cause chrome to show a paused notification and then immediately
change it to progress while killing the browser.
Only progress notification matters, cancel/pause doesn't really matter.

BUG=642191
TBR=dfalcantara@chromium.org

Review-Url: https://codereview.chromium.org/2296913002
Cr-Commit-Position: refs/heads/master@{#415439}
(cherry picked from commit 540399d5f34abfcae1828e2c36835ffae391e319)

Committed: https://chromium.googlesource.com/chromium/src/+/1319e021631140e015810e7ab989212700cecc3c

[qinmin, 2016-09-06 18:01:05]

Description was changed from

==========
Fix an issue that download progress notification is shown when killing browser

When browser gets killed, we should show a paused notification.
However, onTaskRemoved() is often called too early before process fully
stops.
As a result, a progress notification can arrive after Chrome changes all the
notification to paused.
This may cause chrome to show a paused notification and then immediately
change it to progress while killing the browser.
Only progress notification matters, cancel/pause doesn't really matter.

BUG=642191
TBR=dfalcantara@chromium.org

Review-Url: https://codereview.chromium.org/2296913002
Cr-Commit-Position: refs/heads/master@{#415439}
(cherry picked from commit 540399d5f34abfcae1828e2c36835ffae391e319)
==========

to

==========
Fix an issue that download progress notification is shown when killing browser

When browser gets killed, we should show a paused notification.
However, onTaskRemoved() is often called too early before process fully
stops.
As a result, a progress notification can arrive after Chrome changes all the
notification to paused.
This may cause chrome to show a paused notification and then immediately
change it to progress while killing the browser.
Only progress notification matters, cancel/pause doesn't really matter.

BUG=642191
TBR=dfalcantara@chromium.org

Review-Url: https://codereview.chromium.org/2296913002
Cr-Commit-Position: refs/heads/master@{#415439}
(cherry picked from commit 540399d5f34abfcae1828e2c36835ffae391e319)

Committed:
https://chromium.googlesource.com/chromium/src/+/1319e021631140e015810e7ab989...
==========

[qinmin, 2016-09-06 18:01:06]

Committed patchset #1 (id:1) manually as
1319e021631140e015810e7ab989212700cecc3c (presubmit successful).