Set FrameView/OuterViewportContainer size to visible size at minimum scale.

To prevent the inner viewport from becoming larger than the outer viewport
we set the outer viewport's size to be the visible rect at the minimum page
scale.

BUG=364103

Review URL: https://codereview.chromium.org/240863003

git-svn-id: svn://svn.chromium.org/blink/trunk@173147 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Use [TypeChecking=Unrestricted] for MediaController

BUG=354298
TBR=acolwell

Review URL: https://codereview.chromium.org/265743010

git-svn-id: svn://svn.chromium.org/blink/trunk@173148 bbb929c8-8fbe-4397-9dbb-9b2b20218538