[Android] Thoroughly reset gesture detection upon page navigation

      The current gesture reset logic on Android uses a cancellation event
synthesized from the active touch sequence. However, this fails to reset
detection for timeout-based events, e.g. delayed tap and double-tap,
just after the pointer has just been released. Expose an explicit gesture
detection reset hook on the GestureProvider, called when the main
frame navigates or the window loses focus.

BUG=418402

Review URL: https://codereview.chromium.org/717573004

Cr-Commit-Position: refs/heads/master@{#303749}