[Android] Cache function templates in GinJavaBridgeObject to avoid memory leak

[Android] Cache function templates in GinJavaBridgeObject to avoid memory leak

V8 caches all function templates internally for the lifetime of a web page in an
unbounded cache. Thus, creating a new function template for each call to a
method of injected object caused JS heap memory to grow linearly.

This is similar to a fix for Pepper Plugin objects (https://codereview.chromium.org/785213002/)

BUG=462664
Committed: https://crrev.com/8f8de9cf6f95d27dd01b834f2fabcc8389315d37
Cr-Commit-Position: refs/heads/master@{#318890}

[mnaganov (inactive), 2015-03-03 12:51:13]

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

[mnaganov (inactive), 2015-03-03 12:51:13]

PTAL. No tests added because the internal V8 cache is, well, internal, and we
can't test directly that it doesn't grow anymore.

Verified manually with a sample WebView app similar to the one described in the
bug by taking JS heap snapshots with DevTools.

[Torne, 2015-03-03 13:45:10]

lgtm

[mnaganov (inactive), 2015-03-03 13:45:38]

The CQ bit was checked by mnaganov@chromium.org

[commit-bot: I haz the power, 2015-03-03 13:46:38]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/969353004/1

[commit-bot: I haz the power, 2015-03-03 16:35:50]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-03 16:36:29]

Patchset 1 (id:??) landed as
https://crrev.com/8f8de9cf6f95d27dd01b834f2fabcc8389315d37
Cr-Commit-Position: refs/heads/master@{#318890}