Android: ActivityTabWebContentsDelegateAndroid

A new delegate implementation is the one that uses Activity-level
objects to handle the requests delegated from native WebContents. All
WCDAs whose Tab is associated with Activity inherits from this
class. Now TabWebContentsDelegateAndroid is an abstract class that
mostly proxies requests to Tab.

Bug: 960746
Change-Id: Ic371c3354b047f96e721a1299bdb9484c9b83880
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1621466
Commit-Queue: Jinsuk Kim <jinsukkim@chromium.org>
Reviewed-by: Ted Choc <tedchoc@chromium.org>
Cr-Commit-Position: refs/heads/master@{#667850}
8 files changed