Port PPAPI instance tests from nacl_integration to browser_tests.

BUG=154400

Review URL: https://codereview.chromium.org/113163005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@240287 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 240287
Add IBusBridge::GetEngineHandlerById.

I am merging IBusEngineHander to InputMethodManager.  This is a step of the merge.

BUG=N/A

Review URL: https://codereview.chromium.org/97763002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@240288 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 240288