[MediaNotification] Avoid fetching image twice when artwork doesn't change

[MediaNotification] Avoid fetching image twice when artwork doesn't change

When switching src or modifying metadata, the whole metadata will be
sent to MediaSessionTabHelper causing it to download the same image src
twice even if the artwork stays the same. This CL make MediaImageManager
to remember the src of the last downloaded image so that it can avoid
fetch the same src.

BUG=672023
Review-Url: https://codereview.chromium.org/2627103002
Cr-Commit-Position: refs/heads/master@{#443256}
Committed: https://chromium.googlesource.com/chromium/src/+/d9031fa168c6d3a3b2437f56eea99d3c2a16572e

[Zhiqiang Zhang (Slow), 2017-01-11 18:07:41]

zqzhang@chromium.org changed reviewers:
+ mlamouri@chromium.org

[Zhiqiang Zhang (Slow), 2017-01-11 18:07:42]

PTAL (forgive me for sending you too many CLs recently but I think you know more
the context as we discussed on this offline)

After considering different aspects, I think the best solution so far is to
remember the last downloaded src on the client side.

The main reason is that FWIW image fetching should be initiated by MediaSession
clients not from by itself. For our case, it should be fetched by
MediaImageManager. MIM should decide which image is the best (depending on
screen resolution) and MediaSession should not know about it.

Otherwise (MediaSession fetches images and notify clients when images are
available), we need to add new interfaces to MediaSession for clients to specify
which one to fetch. Also we need new signals for letting clients to distinguish
between metadata reset and artwork reset, which is not clean. As all these
signals are passed through content/public API, I don't think content owners will
like it.

WDYT?

[Zhiqiang Zhang (Slow), 2017-01-12 11:13:39]

Description was changed from

==========
[MediaNotification] Avoid fetch image twice when artwork doesn't change

When switching src or modifying metadata, the whole metadata will be
sent to MediaSessionTabHelper causing it to download the same image src
twice even if the artwork stays the same. This CL make MediaImageManager
to remember the src of the last downloaded image so that it can avoid
fetch the same src.

BUG=672023
==========

to

==========
[MediaNotification] Avoid fetching image twice when artwork doesn't change

When switching src or modifying metadata, the whole metadata will be
sent to MediaSessionTabHelper causing it to download the same image src
twice even if the artwork stays the same. This CL make MediaImageManager
to remember the src of the last downloaded image so that it can avoid
fetch the same src.

BUG=672023
==========

[mlamouri (slow - plz ping), 2017-01-12 14:21:30]

The CQ bit was checked by mlamouri@chromium.org

[mlamouri (slow - plz ping), 2017-01-12 14:21:30]

lgtm

I'm not a huge fan of this because it will break the assumptions that we will
try to download the image we are given but I guess it will work as expected for
99% of the use cases. The only case where things would break is if we a website
uses the same image source and decide in the SW which image to return. That
would be fairly weird so unless we hear that people have issues, let's assume
it's fine :)

[commit-bot: I haz the power, 2017-01-12 14:21:49]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-01-12 14:23:32]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2017-01-12 14:23:33]

Try jobs failed on following builders:
  ios-device-xcode-clang on master.tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/ios-device-xcode-...)
  ios-simulator on master.tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/ios-simulator/bui...)

[Zhiqiang Zhang (Slow), 2017-01-12 14:29:52]

The CQ bit was checked by zqzhang@chromium.org

[Zhiqiang Zhang (Slow), 2017-01-12 14:29:52]

The patchset sent to the CQ was uploaded after l-g-t-m from
mlamouri@chromium.org
Link to the patchset: https://codereview.chromium.org/2627103002/#ps20001
(title: "rebased")

[commit-bot: I haz the power, 2017-01-12 14:30:08]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-01-12 15:38:07]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2017-01-12 15:38:08]

Try jobs failed on following builders:
  linux_android_rel_ng on master.tryserver.chromium.android (JOB_FAILED,
https://build.chromium.org/p/tryserver.chromium.android/builders/linux_androi...)

[Zhiqiang Zhang (Slow), 2017-01-12 15:55:26]

The CQ bit was checked by zqzhang@chromium.org

[Zhiqiang Zhang (Slow), 2017-01-12 15:55:26]

The patchset sent to the CQ was uploaded after l-g-t-m from
mlamouri@chromium.org
Link to the patchset: https://codereview.chromium.org/2627103002/#ps40001
(title: "fixed tests")

[commit-bot: I haz the power, 2017-01-12 15:55:45]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-01-12 16:25:59]

CQ is committing da patch.

Bot data: {"patchset_id": 40001, "attempt_start_ts": 1484236526032750,
"parent_rev": "e17314a0eeb014ead59c49754ee6bb2e301dfb2b", "commit_rev":
"d9031fa168c6d3a3b2437f56eea99d3c2a16572e"}

[commit-bot: I haz the power, 2017-01-12 16:26:32]

Description was changed from

==========
[MediaNotification] Avoid fetching image twice when artwork doesn't change

When switching src or modifying metadata, the whole metadata will be
sent to MediaSessionTabHelper causing it to download the same image src
twice even if the artwork stays the same. This CL make MediaImageManager
to remember the src of the last downloaded image so that it can avoid
fetch the same src.

BUG=672023
==========

to

==========
[MediaNotification] Avoid fetching image twice when artwork doesn't change

When switching src or modifying metadata, the whole metadata will be
sent to MediaSessionTabHelper causing it to download the same image src
twice even if the artwork stays the same. This CL make MediaImageManager
to remember the src of the last downloaded image so that it can avoid
fetch the same src.

BUG=672023

Review-Url: https://codereview.chromium.org/2627103002
Cr-Commit-Position: refs/heads/master@{#443256}
Committed:
https://chromium.googlesource.com/chromium/src/+/d9031fa168c6d3a3b2437f56eea9...
==========

[commit-bot: I haz the power, 2017-01-12 16:26:33]

Committed patchset #3 (id:40001) as
https://chromium.googlesource.com/chromium/src/+/d9031fa168c6d3a3b2437f56eea9...