Remove //chrome dependency from ExtensionPrefs

chrome/browser/extensions/chrome_extensions_browser_client.h

Index: chrome/browser/extensions/chrome_extensions_browser_client.h
diff --git a/chrome/browser/extensions/chrome_extensions_browser_client.h b/chrome/browser/extensions/chrome_extensions_browser_client.h
index dd2d46948e0bae7d81ba1993435a1238a9f85980..deb91a99a3f0bd5367fd3dc551d21a201f73d2b0 100644
--- a/chrome/browser/extensions/chrome_extensions_browser_client.h
+++ b/chrome/browser/extensions/chrome_extensions_browser_client.h
@@ -23,6 +23,7 @@ class BrowserContext;
 namespace extensions {
 
 class ChromeExtensionsAPIClient;
+class ContentSettingsPrefsObserver;
 
 // Implementation of extensions::BrowserClient for Chrome, which includes
 // knowledge of Profiles, BrowserContexts and incognito.
@@ -72,6 +73,8 @@ class ChromeExtensionsBrowserClient : public ExtensionsBrowserClient {
   virtual ExtensionSystemProvider* GetExtensionSystemFactory() OVERRIDE;
   virtual void RegisterExtensionFunctions(
       ExtensionFunctionRegistry* registry) const OVERRIDE;
+  virtual void AddExtensionPrefsObservers(content::BrowserContext* context,
+                                          ExtensionPrefs* prefs) const OVERRIDE;
 
  private:
   friend struct base::DefaultLazyInstanceTraits<ChromeExtensionsBrowserClient>;