Add setting to isolate zoom changes by default.

chrome/browser/ui/webui/options/browser_options_handler.h

Index: chrome/browser/ui/webui/options/browser_options_handler.h
diff --git a/chrome/browser/ui/webui/options/browser_options_handler.h b/chrome/browser/ui/webui/options/browser_options_handler.h
index e84a212c72bf8bcf4162297837d3082dd4219bc0..dd3f42de47bd7e80fc00254ea880493b0eaa7d72 100644
--- a/chrome/browser/ui/webui/options/browser_options_handler.h
+++ b/chrome/browser/ui/webui/options/browser_options_handler.h
@@ -257,6 +257,11 @@ class BrowserOptionsHandler
   // one item, the zoom factor as a numeric value.
   void HandleDefaultZoomFactor(const base::ListValue* args);
 
+  // Callback for the "defaultZoomScopeAction" message. This is called if the
+  // user toggles the default zoom scope checkbox.
+  // |args| will contain the checkbox checked state as a boolean.
+  void HandleDefaultZoomScope(const base::ListValue* args);
+
   // Callback for the "Use SSL 3.0" checkbox. This is called if the user toggles
   // the "Use SSL 3.0" checkbox.
   void HandleUseSSL3Checkbox(const base::ListValue* args);
@@ -357,6 +362,9 @@ class BrowserOptionsHandler
   // Setup the page zoom selector control.
   void SetupPageZoomSelector();
 
+  // Setup the default zoom scope checkbox.
+  void SetupZoomScopeCheckbox();
+
   // Setup the visibility of the reset button.
   void SetupAutoOpenFileTypes();
 
@@ -430,6 +438,8 @@ class BrowserOptionsHandler
 
   std::unique_ptr<ChromeZoomLevelPrefs::DefaultZoomLevelSubscription>
       default_zoom_level_subscription_;
+  std::unique_ptr<ChromeZoomLevelPrefs::DefaultZoomScopeSubscription>
+      default_zoom_scope_subscription_;
 
   PrefChangeRegistrar profile_pref_registrar_;
 #if defined(OS_CHROMEOS)