Add setting to isolate zoom changes by default.

content/browser/web_contents/web_contents_impl.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_BROWSER_WEB_CONTENTS_WEB_CONTENTS_IMPL_H_
 #define CONTENT_BROWSER_WEB_CONTENTS_WEB_CONTENTS_IMPL_H_
 
 #include <stdint.h>
 
 #include <functional>
@@ skipping 260 matching lines @@
   RenderFrameHostImpl* FindFrameByFrameTreeNodeId(
       int frame_tree_node_id) override;
   void ForEachFrame(
       const base::Callback<void(RenderFrameHost*)>& on_frame) override;
   std::vector<RenderFrameHost*> GetAllFrames() override;
   int SendToAllFrames(IPC::Message* message) override;
   RenderViewHostImpl* GetRenderViewHost() const override;
   RenderWidgetHostView* GetRenderWidgetHostView() const override;
   RenderWidgetHostView* GetTopLevelRenderWidgetHostView() override;
   void ClosePage() override;
+  void OnReplaced(WebContents* new_contents) override;
   RenderWidgetHostView* GetFullscreenRenderWidgetHostView() const override;
   SkColor GetThemeColor() const override;
   std::unique_ptr<WebUI> CreateSubframeWebUI(
       const GURL& url,
       const std::string& frame_name) override;
   WebUI* GetWebUI() const override;
   WebUI* GetCommittedWebUI() const override;
   void SetUserAgentOverride(const std::string& override) override;
   const std::string& GetUserAgentOverride() const override;
   void EnableWebContentsOnlyAccessibilityMode() override;
@@ skipping 1225 matching lines @@
   // Adds/removes a callback called on creation of each new WebContents.
   static void AddCreatedCallbackForTesting(const CreatedCallback& callback);
   static void RemoveCreatedCallbackForTesting(const CreatedCallback& callback);
 
   DISALLOW_COPY_AND_ASSIGN(FriendZone);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_WEB_CONTENTS_WEB_CONTENTS_IMPL_H_