Changes to content/ to facilitate new zoom extension API

content/public/browser/web_contents_observer.h

Index: content/public/browser/web_contents_observer.h
diff --git a/content/public/browser/web_contents_observer.h b/content/public/browser/web_contents_observer.h
index 9fae539faf6e3a97c3198e6d95a3e703202a7982..ef2486d2378b58916d723226170c70675c7e7089 100644
--- a/content/public/browser/web_contents_observer.h
+++ b/content/public/browser/web_contents_observer.h
@@ -11,6 +11,7 @@
 #include "content/public/browser/navigation_controller.h"
 #include "content/public/common/frame_navigate_params.h"
 #include "content/public/common/page_transition_types.h"
+#include "content/public/common/page_zoom.h"
 #include "ipc/ipc_listener.h"
 #include "ipc/ipc_sender.h"
 #include "ui/base/window_open_disposition.h"
@@ -319,6 +320,11 @@ class CONTENT_EXPORT WebContentsObserver : public IPC::Listener,
   virtual void DidAttachInterstitialPage() {}
   virtual void DidDetachInterstitialPage() {}
 
+  // Invoked when a zoom change is initiated from WebContents::SetZoomLevel().
+  virtual void DidSetZoomLevel(int old_zoom_level,
+                               int new_zoom_level,
+                               ZoomMode zoom_mode) {}
+
   // Invoked before a form repost warning is shown.
   virtual void BeforeFormRepostWarningShow() {}