Use a mock implementation of Platform::crypto() for layout tests.

BUG=245025
R=darin@chromium.org, jochen@chromium.org

Review URL: https://codereview.chromium.org/19594005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@213680 0039d316-1c4b-4281-b951-d872f2087c98
5 files changed