Have a RefPtr take responsibility for the picture's original ref.
Have a RefPtr take responsibility for the picture's original ref.

This should fix the memory leak in the associated bug.
BUG=505781

Review URL: https://codereview.chromium.org/1215163002

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@198096 bbb929c8-8fbe-4397-9dbb-9b2b20218538

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