Add content/content_unittests_run.xml and google_apis/gcm/gcm.xml to .gitignore

These files are added when gyp generating files for VS2010.

R=maruel@chromium.org
NOTRY=True

Review URL: https://codereview.chromium.org/69043002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@234238 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 234238