Allow WebUserMediaClientMock to be used by client
https://bugs.webkit.org/show_bug.cgi?id=113633

Patch by Wei Jia <wjia@chromium.org> on 2013-03-31
Reviewed by Adam Barth.

Export WebUserMediaClientMock.
Allow files in chromium/TestRunner/public to have WEBKIT_EXPORT.

* DumpRenderTree/DumpRenderTree.gypi:
* DumpRenderTree/chromium/TestRunner/public/WebUserMediaClientMock.h: Copied from Tools/DumpRenderTree/chromium/TestRunner/src/WebUserMediaClientMock.h.
(WebUserMediaClientMock):
* DumpRenderTree/chromium/TestRunner/src/WebUserMediaClientMock.h: Removed.
* Scripts/webkitpy/style/checkers/cpp.py:
(check_function_definition):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@147289 268f45cc-cd09-0410-ab3c-d52691b4dbfc