Disable image_decoding_benchmark on android (and linux).

We don't have a general mechanism to differentiate them yet.

BUG=323015
TBR=nduca@chromium.org
NOTRY=True

Review URL: https://codereview.chromium.org/83293009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@236995 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 236995