The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/683cb912ff3612c5ec943e4d45d1426452ebb596

commit 683cb912ff3612c5ec943e4d45d1426452ebb596
Author: ananta <ananta@chromium.org>
Date: Fri Jan 13 01:59:23 2017

PlzNavigate: Fix anchor-no-multiple-windows.html layout test.

This layouttest turns off the WebKitSupportsMultipleWindows property which means that popups
open in the same window. It then initiates a navigation to a data URL by clicking on the
corresponding href. It then compares the window counts and expects the window counts to
remain unchanged.

Without PlzNavigate the data URL navigation creates a provisional loader in blink which
is then cancelled when data is written to the main document, via Document::writeln.

With PlzNavigate the top level navigation for the data URL is sent to the browser. The
provisional loader is created when the navigation is committed via the
FrameMsg_CommitNavigation IPC. This is too late and hence the data written to the page
via the Document::writeln calls never shows up.

Fix is to add a check for whether there is a client side navigation in process for PlzNavigate
and if yes stop ongoing loaders.

BUG= 673744 ,  673742 

Review-Url: https://codereview.chromium.org/2628153002
Cr-Commit-Position: refs/heads/master@{#443458}

[modify] https://crrev.com/683cb912ff3612c5ec943e4d45d1426452ebb596/third_party/WebKit/LayoutTests/FlagExpectations/enable-browser-side-navigation
[modify] https://crrev.com/683cb912ff3612c5ec943e4d45d1426452ebb596/third_party/WebKit/Source/core/dom/Document.cpp
[modify] https://crrev.com/683cb912ff3612c5ec943e4d45d1426452ebb596/third_party/WebKit/Source/core/loader/FrameLoader.cpp
[modify] https://crrev.com/683cb912ff3612c5ec943e4d45d1426452ebb596/third_party/WebKit/Source/core/loader/FrameLoader.h
[modify] https://crrev.com/683cb912ff3612c5ec943e4d45d1426452ebb596/third_party/WebKit/Source/web/WebLocalFrameImpl.cpp