Add setting to isolate zoom changes by default.

chrome/browser/ui/zoom/chrome_zoom_level_prefs.h

Index: chrome/browser/ui/zoom/chrome_zoom_level_prefs.h
diff --git a/chrome/browser/ui/zoom/chrome_zoom_level_prefs.h b/chrome/browser/ui/zoom/chrome_zoom_level_prefs.h
index 4799e23f1ccbadbca9c41d970a89f55e60bbeb4d..9480399bacb4bc2faff40f3f21bfeb7fe5327f4c 100644
--- a/chrome/browser/ui/zoom/chrome_zoom_level_prefs.h
+++ b/chrome/browser/ui/zoom/chrome_zoom_level_prefs.h
@@ -31,7 +31,8 @@ class ZoomEventManager;
 // levels in HostZoomMap and Chrome's preference system. All changes
 // to the per-partition default zoom levels from chrome/ flow through this
 // class. Any changes to per-host levels are updated when HostZoomMap calls
-// OnZoomLevelChanged.
+// OnZoomLevelChanged. This also provides access to the default zoom scope
+// preference.
 class ChromeZoomLevelPrefs : public content::ZoomLevelDelegate {
  public:
   typedef base::CallbackList<void(void)>::Subscription
@@ -55,6 +56,8 @@ class ChromeZoomLevelPrefs : public content::ZoomLevelDelegate {
   std::unique_ptr<DefaultZoomLevelSubscription>
   RegisterDefaultZoomLevelCallback(const base::Closure& callback);
 
+  void SetIsOriginScopePref(bool default_per_origin);
+
   void ExtractPerHostZoomLevels(
       const base::DictionaryValue* host_zoom_dictionary,
       bool sanitize_partition_host_zoom_levels);
@@ -62,6 +65,10 @@ class ChromeZoomLevelPrefs : public content::ZoomLevelDelegate {
   // content::ZoomLevelDelegate
   void InitHostZoomMap(content::HostZoomMap* host_zoom_map) override;
 
+  bool GetIsOriginScopePref() const override;
+  std::unique_ptr<DefaultZoomScopeSubscription>
+  RegisterDefaultZoomScopeCallback(const base::Closure& callback) override;
+
  private:
   // This is a callback function that receives notifications from HostZoomMap
   // when per-host zoom levels change. It is used to update the per-host
@@ -74,6 +81,7 @@ class ChromeZoomLevelPrefs : public content::ZoomLevelDelegate {
   std::unique_ptr<content::HostZoomMap::Subscription> zoom_subscription_;
   std::string partition_key_;
   base::CallbackList<void(void)> default_zoom_changed_callbacks_;
+  base::CallbackList<void(void)> default_scope_changed_callbacks_;
 
   DISALLOW_COPY_AND_ASSIGN(ChromeZoomLevelPrefs);
 };