Make ActivityWindowAndroid per-activity

Make ActivityWindowAndroid per-activity

This is to solve the general perf problem of per-webview
ActivityWindowAndroid when there are a lot of webviews in an activity.
It is kept in a WeakHashMap, and ActivityWindowAndroid only weakly holds
the Activity, to ensure Activity can still be gc-ed.
ActivityWindowAndroid.destroy is called by CleanupReference.

Also make WindowAndroid global and leaking. This is ok since it only uses
the Application.

BUG=487487
Committed: https://crrev.com/4c75e385acc397da59d6b47c04d116e4b3dce1eb
Cr-Commit-Position: refs/heads/master@{#330087}

[boliu, 2015-05-15 03:30:40]

boliu@chromium.org changed reviewers:
+ torne@chromium.org

[boliu, 2015-05-15 03:30:41]

work in process I guess

Best I came up with today. Maybe you can think of something better.

Looks like it might not be safe to call destroy in onActivityDestroyed.
testZoomControlsOnOrientationChange flaking looks like onActivityDestroyed
happened before webview is detached

Maybe it's easier to keep a ref count in the WindowAndroid class. I was hoping
to do this in webview-only code though :/

[boliu, 2015-05-15 03:41:08]

On 2015/05/15 03:30:41, boliu wrote:
> work in process I guess
> 
> Best I came up with today. Maybe you can think of something better.
> 
> Looks like it might not be safe to call destroy in onActivityDestroyed.
> testZoomControlsOnOrientationChange flaking looks like onActivityDestroyed
> happened before webview is detached
> 
> Maybe it's easier to keep a ref count in the WindowAndroid class. I was hoping
> to do this in webview-only code though :/

Actually, maybe a CleanupReference wrapper is better.

[Torne, 2015-05-15 12:48:13]

Generally LGTM, but one question below.

also nit: looks like the commit message needs updating, it still mentions
destroying the WindowAndroid from a listener.

https://codereview.chromium.org/1138113004/diff/40001/android_webview/java/sr...
File android_webview/java/src/org/chromium/android_webview/AwContents.java
(right):

https://codereview.chromium.org/1138113004/diff/40001/android_webview/java/sr...
android_webview/java/src/org/chromium/android_webview/AwContents.java:876:
private static WeakHashMap<Activity, WindowAndroidWrapper> sActivityWindowMap;
The hash map won't release the WindowAndroidWrapper until the activity is GCed,
even if there is no AwContents left which references the WindowAndroidWrapper.
Do we care if the ActivityWindowAndroid always lives as long as the Activity,
even when there's no WebView currently in existence? Probably fine..

[boliu, 2015-05-15 13:34:01]

https://codereview.chromium.org/1138113004/diff/40001/android_webview/java/sr...
File android_webview/java/src/org/chromium/android_webview/AwContents.java
(right):

https://codereview.chromium.org/1138113004/diff/40001/android_webview/java/sr...
android_webview/java/src/org/chromium/android_webview/AwContents.java:876:
private static WeakHashMap<Activity, WindowAndroidWrapper> sActivityWindowMap;
On 2015/05/15 12:48:13, Torne wrote:
> The hash map won't release the WindowAndroidWrapper until the activity is
GCed,
> even if there is no AwContents left which references the WindowAndroidWrapper.
> Do we care if the ActivityWindowAndroid always lives as long as the Activity,
> even when there's no WebView currently in existence? Probably fine..

Yeah I think that's fine. If another webview is created in the same activity,
the ActivityWindowAndroid will be reused, so it's not really "leaking".

[boliu, 2015-05-15 13:38:11]

The CQ bit was checked by boliu@chromium.org

[commit-bot: I haz the power, 2015-05-15 13:38:35]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1138113004/40001

[commit-bot: I haz the power, 2015-05-15 13:41:51]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2015-05-15 13:42:41]

Patchset 3 (id:??) landed as
https://crrev.com/4c75e385acc397da59d6b47c04d116e4b3dce1eb
Cr-Commit-Position: refs/heads/master@{#330087}