Add heuristics to limit showing of new backspace UI bubble.

chrome/test/base/test_browser_window.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/test/base/test_browser_window.h"
 
 #include "base/memory/ptr_util.h"
 #include "build/build_config.h"
 #include "chrome/browser/ui/browser_list.h"
 #include "chrome/browser/ui/browser_list_observer.h"
@@ skipping 101 matching lines @@
 }
 
 bool TestBrowserWindow::IsFullscreen() const {
   return false;
 }
 
 bool TestBrowserWindow::IsFullscreenBubbleVisible() const {
   return false;
 }
 
-void TestBrowserWindow::ShowNewBackShortcutBubble(bool forward) {}
-
 LocationBar* TestBrowserWindow::GetLocationBar() const {
   return const_cast<TestLocationBar*>(&location_bar_);
 }
 
 ToolbarActionsBar* TestBrowserWindow::GetToolbarActionsBar() {
   return nullptr;
 }
 
 bool TestBrowserWindow::PreHandleKeyboardEvent(
     const content::NativeWebKeyboardEvent& event,
@@ skipping 74 matching lines @@
 }
 
 TestBrowserWindowOwner::~TestBrowserWindowOwner() {
   BrowserList::RemoveObserver(this);
 }
 
 void TestBrowserWindowOwner::OnBrowserRemoved(Browser* browser) {
   if (browser->window() == window_.get())
     delete this;
 }