Initial SavedPages eventlogging for iOS

now with the actual classes

Change-Id: Iba7164704a950e53a60988f194787fa97b4415fd
Fix for share button on iPad

Activity view controller must be presented in a popup on iPad,
but we were presenting it modally. This started crashing on
iOS 8. Nice! So, let's fix it.

Amended to fix "popover dealloc'ed while popover still
visible" crash on iPad 2 iOS 7.1 simulator.

Bug: 71189
Change-Id: I6da0feff6b415b9ac6e23bf712b85baf3a14188e
Work in progress.

Change-Id: I68b7bd593e667cc39da853651fbb04511143cd90