[SPv175] Fix embedded frame invalidation and painting

Embedded frame invalidation/painting goes through PlatformChromeClient.

- Invalidate PlatformChromeClient when any content in the embedded frame
  is invalidated;

- Apply InnerBorderRadiusClip when painting embedded contents.

Bug: 771643
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
Change-Id: I1b2796a45f4e48f6912dddd820f33e18ec62e9f1
Reviewed-on: https://chromium-review.googlesource.com/879127
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#531050}
9 files changed