Add and log SimpleCache.Media.* histograms.

The giant histograms.xml change just duplicates all of the (non-obsolete) SimpleCache.App.* histograms as SimpleCache.Media.*.

BUG=280585,314848

Review URL: https://codereview.chromium.org/64703002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@233852 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 233852
[I-Spy] Remove DOM stability check from chrome_utils.

It required a dependency on webdriver which is better kept in the
downstream test.

BUG=None
TEST=None
NOTRY=True

Review URL: https://codereview.chromium.org/64713005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@233853 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 233853