Number of small improvements to CleanupReference

Number of small improvements to CleanupReference

- sRef is now only accessed on main thread, so CleanupReference should
  now be threadsafe
- synchronously flushes sQueue when references added or removed on main
  thread, to avoid falling behind when heap is churning rapidly (i.e.
  finalizers never getting to run scenario).
- ensure the referene gets removed from sRefs after a GC as otherwise
  it might have remained on there indefinitely.

BUG=


Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=174931

[David Trainor- moved to gerrit, 2013-01-02 18:54:00]

lgtm with one nit/suggestion

https://codereview.chromium.org/11648040/diff/1/content/public/android/java/s...
File
content/public/android/java/src/org/chromium/content/common/CleanupReference.java
(right):

https://codereview.chromium.org/11648040/diff/1/content/public/android/java/s...
content/public/android/java/src/org/chromium/content/common/CleanupReference.java:54:
// Remove new reference to sRefs. msg.obj is the CleanupReference to remove.
"Remove new reference to sRefs" --> "Remove reference from sRefs"?

https://codereview.chromium.org/11648040/diff/1/content/public/android/java/s...
content/public/android/java/src/org/chromium/content/common/CleanupReference.java:73:
sRefs.remove(ref);
You duplicate this code below in the while loop.  Worth putting into some
private method?  Not really necessary, just an idea.

[joth, 2013-01-03 00:30:49]

+ted for OWNER review.

Thanks!

https://codereview.chromium.org/11648040/diff/1/content/public/android/java/s...
File
content/public/android/java/src/org/chromium/content/common/CleanupReference.java
(right):

https://codereview.chromium.org/11648040/diff/1/content/public/android/java/s...
content/public/android/java/src/org/chromium/content/common/CleanupReference.java:54:
// Remove new reference to sRefs. msg.obj is the CleanupReference to remove.
On 2013/01/02 18:54:00, dtrainor wrote:
> "Remove new reference to sRefs" --> "Remove reference from sRefs"?

Done.

https://codereview.chromium.org/11648040/diff/1/content/public/android/java/s...
content/public/android/java/src/org/chromium/content/common/CleanupReference.java:73:
sRefs.remove(ref);
On 2013/01/02 18:54:00, dtrainor wrote:
> You duplicate this code below in the while loop.  Worth putting into some
> private method?  Not really necessary, just an idea.

Done.
runCleanupTaskInternal() can do it all.

[Ted C, 2013-01-03 01:22:05]

lgtm

[commit-bot: I haz the power, 2013-01-03 01:47:41]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/joth@chromium.org/11648040/6001

[commit-bot: I haz the power, 2013-01-03 03:40:53]

Change committed as 174931