WIP CL @ https://crrev.com/c/1228944

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/59aed3764077ffd201c04490e81801d6a24ed9f2

commit 59aed3764077ffd201c04490e81801d6a24ed9f2
Author: Lukasz Anforowicz <lukasza@chromium.org>
Date: Mon Oct 01 23:32:17 2018

Remove code related to Top Document Isolation (TDI) feature.

We've decided to not ship this feature and focus on other isolation
modes instead.

Bug:  884842 
Change-Id: I5895e12f4c80fa22e9fef8ea7045a1bb6a7913bb
Reviewed-on: https://chromium-review.googlesource.com/1228944
Reviewed-by: Nasko Oskov <nasko@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Commit-Queue: Łukasz Anforowicz <lukasza@chromium.org>
Cr-Commit-Position: refs/heads/master@{#595635}
[modify] https://crrev.com/59aed3764077ffd201c04490e81801d6a24ed9f2/chrome/app/generated_resources.grd
[modify] https://crrev.com/59aed3764077ffd201c04490e81801d6a24ed9f2/chrome/browser/about_flags.cc
[modify] https://crrev.com/59aed3764077ffd201c04490e81801d6a24ed9f2/chrome/browser/chrome_content_browser_client.cc
[modify] https://crrev.com/59aed3764077ffd201c04490e81801d6a24ed9f2/chrome/browser/chrome_content_browser_client.h
[modify] https://crrev.com/59aed3764077ffd201c04490e81801d6a24ed9f2/chrome/browser/extensions/chrome_content_browser_client_extensions_part.cc
[modify] https://crrev.com/59aed3764077ffd201c04490e81801d6a24ed9f2/chrome/browser/extensions/chrome_content_browser_client_extensions_part.h
[modify] https://crrev.com/59aed3764077ffd201c04490e81801d6a24ed9f2/chrome/browser/flag_descriptions.cc
[modify] https://crrev.com/59aed3764077ffd201c04490e81801d6a24ed9f2/chrome/browser/flag_descriptions.h
[modify] https://crrev.com/59aed3764077ffd201c04490e81801d6a24ed9f2/chrome/browser/task_manager/providers/web_contents/subframe_task.cc
[modify] https://crrev.com/59aed3764077ffd201c04490e81801d6a24ed9f2/chrome/browser/task_manager/providers/web_contents/subframe_task_browsertest.cc
[modify] https://crrev.com/59aed3764077ffd201c04490e81801d6a24ed9f2/chrome/browser/ui/extensions/hosted_app_browsertest.cc
[modify] https://crrev.com/59aed3764077ffd201c04490e81801d6a24ed9f2/content/browser/browsing_instance.cc
[modify] https://crrev.com/59aed3764077ffd201c04490e81801d6a24ed9f2/content/browser/browsing_instance.h
[modify] https://crrev.com/59aed3764077ffd201c04490e81801d6a24ed9f2/content/browser/frame_host/render_frame_host_manager.cc
[modify] https://crrev.com/59aed3764077ffd201c04490e81801d6a24ed9f2/content/browser/frame_host/render_frame_host_manager.h
[modify] https://crrev.com/59aed3764077ffd201c04490e81801d6a24ed9f2/content/browser/process_internals/process_internals_handler_impl.cc
[modify] https://crrev.com/59aed3764077ffd201c04490e81801d6a24ed9f2/content/browser/renderer_host/render_process_host_impl.cc
[modify] https://crrev.com/59aed3764077ffd201c04490e81801d6a24ed9f2/content/browser/renderer_host/render_process_host_impl.h
[modify] https://crrev.com/59aed3764077ffd201c04490e81801d6a24ed9f2/content/browser/site_instance_impl.cc
[modify] https://crrev.com/59aed3764077ffd201c04490e81801d6a24ed9f2/content/browser/site_instance_impl.h
[modify] https://crrev.com/59aed3764077ffd201c04490e81801d6a24ed9f2/content/browser/site_instance_impl_unittest.cc
[delete] https://crrev.com/d45d21dcb78c52143d7044a62c6ae3d0b12be21a/content/browser/top_document_isolation_browsertest.cc
[modify] https://crrev.com/59aed3764077ffd201c04490e81801d6a24ed9f2/content/public/browser/content_browser_client.cc
[modify] https://crrev.com/59aed3764077ffd201c04490e81801d6a24ed9f2/content/public/browser/content_browser_client.h
[modify] https://crrev.com/59aed3764077ffd201c04490e81801d6a24ed9f2/content/public/browser/site_instance.h
[modify] https://crrev.com/59aed3764077ffd201c04490e81801d6a24ed9f2/content/public/browser/site_isolation_policy.cc
[modify] https://crrev.com/59aed3764077ffd201c04490e81801d6a24ed9f2/content/public/browser/site_isolation_policy.h
[modify] https://crrev.com/59aed3764077ffd201c04490e81801d6a24ed9f2/content/public/common/content_features.cc
[modify] https://crrev.com/59aed3764077ffd201c04490e81801d6a24ed9f2/content/public/common/content_features.h
[modify] https://crrev.com/59aed3764077ffd201c04490e81801d6a24ed9f2/content/test/BUILD.gn
[modify] https://crrev.com/59aed3764077ffd201c04490e81801d6a24ed9f2/content/test/content_browser_test_utils_internal.cc