[Android] Revert for regression where gestures interrupted on page load

This is a partial revert of https://codereview.chromium.org/120203003.
It is quite common for a page to generate multiple |DidStartLoading()|
notifications while it finishes loading.  Redundant notifications should
not reset a gesture mid-sequence.

BUG=335586

Review URL: https://codereview.chromium.org/141853002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@245630 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 245630