Avoid dereferencing NULL pointer on session creation failure.
Avoid dereferencing NULL pointer on session creation failure.

If the session initialization fails (for example, attempting to read the client's process information) then the buffer_consumer_ member will still be NULL when the destructor is subsequently called.

BUG=
TEST=

Review URL: https://codereview.appspot.com/6257057

git-svn-id: db59699583a60be9a535cd09cdc9132301867226@847 15e8cca8-e42c-11de-a347-f34a4f72eb7d

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