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This adds the API to SSLClientSocket but does not yet hook it up
to the rest of the stack.

Bug: 641225
Change-Id: I8694d4e4f92d7e57d32541fcc2b87ed5fb42d075
Reviewed-on: https://chromium-review.googlesource.com/1067639
Commit-Queue: Steven Valdez <svaldez@chromium.org>
Reviewed-by: Steven Valdez <svaldez@chromium.org>
Reviewed-by: David Benjamin <davidben@chromium.org>
Cr-Commit-Position: refs/heads/master@{#575189}