Move ChromeShell files from chrome/android/testshell to chrome/android/shell.

BUG=348137
NOTRY=true

Review URL: https://codereview.chromium.org/186843002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255258 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 255258