Remove content::NotificationObserver dependency from most Prefs code.

chrome/browser/printing/print_view_manager.h

Index: chrome/browser/printing/print_view_manager.h
diff --git a/chrome/browser/printing/print_view_manager.h b/chrome/browser/printing/print_view_manager.h
index e23eaab7ff951ef148c0089b1198ac604bf1cf01..d83c1a325e4ba9b7bc4fb3458a1aba467f4060ca 100644
--- a/chrome/browser/printing/print_view_manager.h
+++ b/chrome/browser/printing/print_view_manager.h
@@ -6,6 +6,7 @@
 #define CHROME_BROWSER_PRINTING_PRINT_VIEW_MANAGER_H_
 
 #include "base/memory/ref_counted.h"
+#include "base/prefs/public/pref_observer.h"
 #include "base/string16.h"
 #include "chrome/browser/api/prefs/pref_member.h"
 #include "content/public/browser/notification_observer.h"
@@ -30,6 +31,7 @@ class PrintViewManagerObserver;
 
 // Manages the print commands for a WebContents.
 class PrintViewManager : public content::NotificationObserver,
+                         public PrefObserver,
                          public PrintedPagesSource,
                          public content::WebContentsObserver,
                          public content::WebContentsUserData<PrintViewManager> {
@@ -77,6 +79,10 @@ class PrintViewManager : public content::NotificationObserver,
   // must be NULL if |observer| is non-NULL.
   void set_observer(PrintViewManagerObserver* observer);
 
+  // PrefObserver implementation.
+  virtual void OnPreferenceChanged(PrefServiceBase* service,
+                                   const std::string& pref_name) OVERRIDE;
+
   // PrintedPagesSource implementation.
   virtual string16 RenderSourceName() OVERRIDE;