Add setting to isolate zoom changes by default.

content/public/browser/web_contents_observer.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_OBSERVER_H_
 #define CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_OBSERVER_H_
 
 #include <stdint.h>
 
 #include "base/macros.h"
@@ skipping 388 matching lines @@
   // before it's used for anything in case there's an exploited renderer
   // process.
   virtual void PluginHungStatusChanged(int plugin_child_id,
                                        const base::FilePath& plugin_path,
                                        bool is_hung) {}
 
   // Invoked when WebContents::Clone() was used to clone a WebContents.
   virtual void DidCloneToNewWebContents(WebContents* old_web_contents,
                                         WebContents* new_web_contents) {}
 
+  // Invoked when a tab's WebContents is replaced with another.

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

Ditto.

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

Done.

Removed.

+  virtual void WebContentsReplaced(WebContents* old_web_contents,
+                                   WebContents* new_web_contents) {}
+
   // Invoked when the WebContents is being destroyed. Gives subclasses a chance
   // to cleanup. After the whole loop over all WebContentsObservers has been
   // finished, web_contents() returns nullptr.
   virtual void WebContentsDestroyed() {}
 
   // Called when the user agent override for a WebContents has been changed.
   virtual void UserAgentOverrideSet(const std::string& user_agent) {}
 
   // Invoked when new FaviconURL candidates are received from the renderer
   // process.
@@ skipping 92 matching lines @@
   void ResetWebContents();
 
   WebContentsImpl* web_contents_;
 
   DISALLOW_COPY_AND_ASSIGN(WebContentsObserver);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_WEB_CONTENTS_OBSERVER_H_