[Android] Fix a subtle issue in Java Bridge regarding interfaces removal

[Android] Fix a subtle issue in Java Bridge regarding interfaces removal

Update JavaBridgeBasicsTest.testRemovalNotReflectedUntilReload to actually
call Java GC after removing the interface, and verify that the Java object
is still callable from the page side. Fix the code to make the test pass.

BUG=437761
Committed: https://crrev.com/4d4182c4af0a11a1ad5acae88f9abe2b76853fe1
Cr-Commit-Position: refs/heads/master@{#306176}

[mnaganov (inactive), 2014-12-01 10:59:50]

mnaganov@chromium.org changed reviewers:
+ benm@chromium.org

[mnaganov (inactive), 2014-12-01 10:59:51]

Ben, PTAL!

I've noticed the issue while working on the background thread bug.

[benm (inactive), 2014-12-01 11:08:03]

lgtm

[mnaganov (inactive), 2014-12-01 11:09:06]

The CQ bit was checked by mnaganov@chromium.org

[commit-bot: I haz the power, 2014-12-01 11:09:31]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/767453003/1

[commit-bot: I haz the power, 2014-12-01 11:59:21]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-12-01 12:00:02]

Patchset 1 (id:??) landed as
https://crrev.com/4d4182c4af0a11a1ad5acae88f9abe2b76853fe1
Cr-Commit-Position: refs/heads/master@{#306176}