Make URLRequestThrottlerManager a member of URLRequestContext.

chrome/browser/io_thread.h

Index: chrome/browser/io_thread.h
diff --git a/chrome/browser/io_thread.h b/chrome/browser/io_thread.h
index 51d2ead61644a6fe2159e7dba8d810bde38a63c1..270b4c8e764881d436a251e1ed24d6919ed58e4c 100644
--- a/chrome/browser/io_thread.h
+++ b/chrome/browser/io_thread.h
@@ -46,6 +46,7 @@ class SSLConfigService;
 class TransportSecurityState;
 class URLRequestContext;
 class URLRequestContextGetter;
+class URLRequestThrottlerManager;
 class URLSecurityManager;
 }  // namespace net
 
@@ -107,6 +108,7 @@ class IOThread : public content::BrowserThreadDelegate {
         extension_event_router_forwarder;
     scoped_ptr<chrome_browser_net::HttpPipeliningCompatibilityClient>
         http_pipelining_compatibility_client;
+    scoped_ptr<net::URLRequestThrottlerManager> throttler_manager;
   };
 
   // |net_log| must either outlive the IOThread or be NULL.