Don't instantiate a UserGestureIndicator in WebPluginContainerImpl

Either the plugin gets the event via EventHandler, then there is already
a gesture indicator on the stack, or if the plugin has mouse lock and gets
the events directly from the WebViewImpl, the WebViewImpl should manage
the gesture indicator.

BUG=364405
TEST=plugins/user-gesture.html still works
R=abarth@chromium.org

Review URL: https://codereview.chromium.org/240033007

git-svn-id: svn://svn.chromium.org/blink/trunk@171900 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Delete HistoryController and associated plumbing

It is dead code as of http://src.chromium.org/viewvc/chrome?view=revision&revision=263767

BUG=357327

Review URL: https://codereview.chromium.org/239183004

git-svn-id: svn://svn.chromium.org/blink/trunk@171901 bbb929c8-8fbe-4397-9dbb-9b2b20218538