Fix the WebStrings leak in MockWebClipboardImpl

Fix the WebString leak in MockWebClipboardImpl

When we run content_shell in the single process mode with tests using the clipboard, the renderer thread passes WebString to the browser thread. It causes leak.
To avoid this, change the member WebString to NullableString16.

BUG=328158
TEST=content_shell --dump-render-tree --single-process ../../third_party/WebKit/LayoutTests/editing/pasteboard/createMarkup-assert.xml

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=247850

[yoichio, 2014-01-27 02:21:59]

Could you review?

[dcheng, 2014-01-27 19:47:04]

https://codereview.chromium.org/135853010/diff/160001/content/test/mock_webcl...
File content/test/mock_webclipboard_impl.cc (right):

https://codereview.chromium.org/135853010/diff/160001/content/test/mock_webcl...
content/test/mock_webclipboard_impl.cc:42: return !m_plainText.empty();
The difference between empty and null is significant. Perhaps use
NullableString16?

[yoichio, 2014-01-28 07:57:21]

Nice suggest! NullableString16 fits this issue.
Thanks.

[dcheng, 2014-01-28 23:42:48]

lgtm

[commit-bot: I haz the power, 2014-01-28 23:48:18]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/yoichio@chromium.org/135853010/200001

[commit-bot: I haz the power, 2014-01-29 00:09:25]

Retried try job too often on chromium_presubmit for step(s) presubmit
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=chromium_p...

[yoichio, 2014-01-29 01:38:02]

+sky@ as an OWNER.
Could you look?

[sky, 2014-01-29 16:43:24]

LGTM

[commit-bot: I haz the power, 2014-01-29 22:42:59]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/yoichio@chromium.org/135853010/200001

[commit-bot: I haz the power, 2014-01-30 06:19:47]

Change committed as 247850