Add placeholder directories so the chromium canary bots can update.
Add placeholder directories so the chromium canary bots can update.

* platform/chromium-mac: Added.
* platform/chromium-mac/fast: Added.
* platform/chromium-mac/fast/events: Added.
* platform/chromium-mac/http: Added.
* platform/chromium-mac/http/tests: Added.
* platform/chromium-mac/http/tests/workers: Added.
* platform/chromium-mac/storage: Added.
* platform/chromium-mac/storage/domstorage: Added.


git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@93172 bbb929c8-8fbe-4397-9dbb-9b2b20218538
primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs