Introduce a delegate to avoid hardcoding "chrome-extension" in net/.

chrome/browser/net/chrome_network_delegate.h

Index: chrome/browser/net/chrome_network_delegate.h
diff --git a/chrome/browser/net/chrome_network_delegate.h b/chrome/browser/net/chrome_network_delegate.h
index dda92d5a556aaa25c42fb5278872cd4a6f213eca..2ff6843669c5ec47a779588403f79288a860fa07 100644
--- a/chrome/browser/net/chrome_network_delegate.h
+++ b/chrome/browser/net/chrome_network_delegate.h
@@ -42,6 +42,9 @@ class ChromeNetworkDelegate : public net::NetworkDelegate {
       BooleanPrefMember* enable_referrers);
   virtual ~ChromeNetworkDelegate();
 
+  // Causes |OnCanThrottleRequest| to never return true.
+  void NeverThrottleRequests();
+
   // Binds |enable_referrers| to |pref_service| and moves it to the IO thread.
   // This method should be called on the UI thread.
   static void InitializeReferrersEnabled(BooleanPrefMember* enable_referrers,
@@ -88,6 +91,8 @@ class ChromeNetworkDelegate : public net::NetworkDelegate {
                               net::CookieOptions* options) OVERRIDE;
   virtual bool OnCanAccessFile(const net::URLRequest& request,
                                const FilePath& path) const OVERRIDE;
+  virtual bool OnCanThrottleRequest(
+      const net::URLRequest& request) const OVERRIDE;
 
   scoped_refptr<ExtensionEventRouterForwarder> event_router_;
   void* profile_;
@@ -98,6 +103,9 @@ class ChromeNetworkDelegate : public net::NetworkDelegate {
   // Weak, owned by our owner.
   BooleanPrefMember* enable_referrers_;
 
+  // True if OnCanThrottleRequest should always return false.
+  bool never_throttle_requests_;
+
   // Weak, owned by our owner.
   const policy::URLBlacklistManager* url_blacklist_manager_;