Make KitkatCaptioningBridge a singleton

Make KitkatCaptioningBridge a singleton

Currently each ContentViewCore creates a KitkatCaptioningBridge on K+ devices.
And all of them listens to the system CaptioningManager.
So whenever the system captioning changes, all ContentViewCores will have to handle it separately.
This change simplifies that process by making KitkatCaptioningBridge a singleton.
All ContentViewCores become listeners to that singleton.
Whenever system captioning changes, a single CaptioningChangeDelegate class will handle the change.
It will then inform all ContentViewCores that are alive.
If all ContentViewCores are GC'ed, KitkatCaptioningBridge will stop listen to system CaptioningManager.

BUG=457850
Committed: https://crrev.com/ef83a816a5494cc0eb6b6f6ae7a22464b7624f3d
Cr-Commit-Position: refs/heads/master@{#330408}

[qinmin, 2015-05-15 23:46:19]

qinmin@chromium.org changed reviewers:
+ dtrainor@chromium.org

[qinmin, 2015-05-15 23:46:20]

PTAL

[David Trainor- moved to gerrit, 2015-05-18 14:01:24]

lgtm

https://chromiumcodereview.appspot.com/1132053005/diff/1/content/public/andro...
File
content/public/android/java/src/org/chromium/content/browser/accessibility/captioning/EmptyCaptioningBridge.java
(right):

https://chromiumcodereview.appspot.com/1132053005/diff/1/content/public/andro...
content/public/android/java/src/org/chromium/content/browser/accessibility/captioning/EmptyCaptioningBridge.java:12:
private static EmptyCaptioningBridge sEmptyCaptioningBridge;
remove?

[qinmin, 2015-05-18 18:29:26]

https://codereview.chromium.org/1132053005/diff/1/content/public/android/java...
File
content/public/android/java/src/org/chromium/content/browser/accessibility/captioning/EmptyCaptioningBridge.java
(right):

https://codereview.chromium.org/1132053005/diff/1/content/public/android/java...
content/public/android/java/src/org/chromium/content/browser/accessibility/captioning/EmptyCaptioningBridge.java:12:
private static EmptyCaptioningBridge sEmptyCaptioningBridge;
On 2015/05/18 14:01:24, David Trainor wrote:
> remove?

Done.

[qinmin, 2015-05-18 18:29:31]

The CQ bit was checked by qinmin@chromium.org

[qinmin, 2015-05-18 18:29:31]

The patchset sent to the CQ was uploaded after l-g-t-m from
dtrainor@chromium.org
Link to the patchset: https://codereview.chromium.org/1132053005/#ps20001
(title: "remove unused singleton")

[commit-bot: I haz the power, 2015-05-18 18:31:02]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1132053005/20001

[commit-bot: I haz the power, 2015-05-18 20:45:39]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-05-18 22:42:40]

Patchset 2 (id:??) landed as
https://crrev.com/ef83a816a5494cc0eb6b6f6ae7a22464b7624f3d
Cr-Commit-Position: refs/heads/master@{#330408}