Blink: remove PlatformFrameView and simplify PlatformChromeClient

Most of this stuff is unused.

Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
Change-Id: Ifd45c91b507d100e6703f93ed9dbe569c44dd127
Reviewed-on: https://chromium-review.googlesource.com/1065141
Reviewed-by: Jeremy Roman <jbroman@chromium.org>
Commit-Queue: Dmitry Gozman <dgozman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#559912}
27 files changed