Add setting to isolate zoom changes by default.

content/public/browser/web_contents.h

 // 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.
 
 #ifndef CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_H_
 #define CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 259 matching lines @@
   // Returns the outermost RenderWidgetHostView. This will return the platform
   // specific RenderWidgetHostView (as opposed to
   // RenderWidgetHostViewChildFrame), which can be used to create context
   // menus.
   virtual RenderWidgetHostView* GetTopLevelRenderWidgetHostView() = 0;
 
   // Causes the current page to be closed, including running its onunload event
   // handler.
   virtual void ClosePage() = 0;
 
+  // Notifies the WebContents of its replacement by another WebContents
+  // in a browser tab.
+  virtual void OnReplaced(WebContents* new_contents) = 0;

[wjmaclean, 2017/01/19 21:09:06]

Hmm, content/ isn't supposed to know anything about "tabs", so we'll need some
other description for this, or move the concept into chrome/.

[Kevin McNee, 2017/01/25 23:42:56]

Done.

Removed.

+
   // Returns the currently active fullscreen widget. If there is none, returns
   // nullptr.
   virtual RenderWidgetHostView* GetFullscreenRenderWidgetHostView() const = 0;
 
   // Returns the theme color for the underlying content as set by the
   // theme-color meta tag.
   virtual SkColor GetThemeColor() const = 0;
 
   // Create a WebUI page for the given url. In most cases, this doesn't need to
   // be called by embedders since content will create its own WebUI objects as
@@ skipping 475 matching lines @@
 
  private:
   // This interface should only be implemented inside content.
   friend class WebContentsImpl;
   WebContents() {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_H_