GitLab

This CL is the 4th in a series of changes that straddle webkit vs chromium repositories.
1) WK: Declare new virtual createSnapshotFile/didCreateSnapshotFile public api methods.
2) CR: Implement the new create method such that the didCreate method is invoked in response.
3) WK: Use the new create method and implement the new didCreate method.
4) CR: Cleanup the obsolete/deprecated blocks of code.

BUG=174200

Review URL: https://codereview.chromium.org/13891009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@194648 0039d316-1c4b-4281-b951-d872f2087c98