[Android] Disable double-tap gesture detection with fixed page scale

Double-tap gestures, either for zoom or drag zoom, have no effect when the page
scale is fixed.  Disable double-tap gesture detection completely in this case,
allowing fast sequential tapping, eliminating associated gesture detection
delays and suppressing spurious pinch event sequences.

BUG=295906

Review URL: https://codereview.chromium.org/27043004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@228603 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 228603