Switch MHTMLGenerationManager to use a Callback.

chrome/browser/extensions/extension_save_page_api.h

Index: chrome/browser/extensions/extension_save_page_api.h
diff --git a/chrome/browser/extensions/extension_save_page_api.h b/chrome/browser/extensions/extension_save_page_api.h
index 106cd5a604136ef61dd34c8946cc7dee1356d689..fc7ce9afd4d6a2f9da2cc1a43ab3000e581fbc37 100644
--- a/chrome/browser/extensions/extension_save_page_api.h
+++ b/chrome/browser/extensions/extension_save_page_api.h
@@ -10,12 +10,11 @@
 #include "base/memory/ref_counted.h"
 #include "chrome/browser/extensions/extension_function.h"
 #include "content/browser/tab_contents/tab_contents_observer.h"
-#include "content/public/browser/notification_observer.h"
-#include "content/public/browser/notification_registrar.h"
 #include "webkit/blob/deletable_file_reference.h"
 
-class SavePageAsMHTMLFunction : public AsyncExtensionFunction,
-                                public content::NotificationObserver {
+class FilePath;
+
+class SavePageAsMHTMLFunction : public AsyncExtensionFunction {
  public:
   SavePageAsMHTMLFunction();
 
@@ -31,9 +30,6 @@ class SavePageAsMHTMLFunction : public AsyncExtensionFunction,
  private:
   virtual ~SavePageAsMHTMLFunction();
   virtual bool RunImpl() OVERRIDE;
-  virtual void Observe(int type,
-                       const content::NotificationSource& source,
-                       const content::NotificationDetails& details) OVERRIDE;
   virtual bool OnMessageReceivedFromRenderView(
       const IPC::Message& message) OVERRIDE;
 
@@ -45,6 +41,9 @@ class SavePageAsMHTMLFunction : public AsyncExtensionFunction,
   void ReturnFailure(const std::string& error);
   void ReturnSuccess(int64 file_size);
 
+  // Callback called once the MHTML generation is done.
+  void MHTMLGenerated(const FilePath& file_path, int64 mhtml_file_size);
+
   // Returns the TabContents we are associated with, NULL if it's been closed.
   TabContents* GetTabContents();
 
@@ -56,8 +55,6 @@ class SavePageAsMHTMLFunction : public AsyncExtensionFunction,
   // The file containing the MHTML.
   scoped_refptr<webkit_blob::DeletableFileReference> mhtml_file_;
 
-  content::NotificationRegistrar registrar_;
-
   DECLARE_EXTENSION_FUNCTION_NAME("experimental.savePage.saveAsMHTML")
 };