Fix a potential assert in SpeechRecognizer dtor. When StopRecognition is invoked and no data was recorded, there is a possibility that the delegate might release the recognizer within the DidCompleteRecognition callback. So we now perform cleanup tasks such as freeing the encoder_ object before invoking the delegate. Without this change there would be an assert in the SpeechRecognizer dtor about encoder_ remaining valid.
Fix a potential assert in SpeechRecognizer dtor.
When StopRecognition is invoked and no data was recorded, there is a possibility that the delegate
might release the recognizer within the DidCompleteRecognition callback. So we now perform cleanup
tasks such as freeing the encoder_ object before invoking the delegate. Without this change there
would be an assert in the SpeechRecognizer dtor about encoder_ remaining valid.

BUG=none
TEST=Manual, double-click on the speech button quickly a few times and verify no assert pops up in the dtor.

Review URL: http://codereview.chromium.org/6381004

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@71994 0039d316-1c4b-4281-b951-d872f2087c98

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