Don't throttle unless origin schema is chrome-extension.

net/url_request/url_request_http_job.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/url_request/url_request_http_job.h"
 
 #include "base/base_switches.h"
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/command_line.h"
@@ skipping 302 matching lines @@
   if (transaction_.get()) {
     rv = transaction_->RestartWithAuth(auth_credentials_, start_callback_);
     auth_credentials_ = AuthCredentials();
   } else {
     DCHECK(request_->context());
     DCHECK(request_->context()->http_transaction_factory());
 
     rv = request_->context()->http_transaction_factory()->CreateTransaction(
         &transaction_);
     if (rv == OK) {
+      // TODO(joi): The hard-coded check for "chrome-extension" is
+      // temporary (as of 2012/3/21), intended only to make sure this
+      // change (to throttle only requests originating from
+      // extensions) gets into M19. Right after the M19 branch point,
+      // I will sort this out in a more architecturally-sound way.
       if (!URLRequestThrottlerManager::GetInstance()->enforce_throttling() ||
+          request_->first_party_for_cookies().scheme() != "chrome-extension" ||
           !throttling_entry_->ShouldRejectRequest(request_info_.load_flags)) {
         rv = transaction_->Start(
             &request_info_, start_callback_, request_->net_log());
         start_time_ = base::TimeTicks::Now();
       } else {
         // Special error code for the exponential back-off module.
         rv = ERR_TEMPORARILY_THROTTLED;
       }
       // Make sure the context is alive for the duration of the
       // transaction.
@@ skipping 1075 matching lines @@
   return override_response_headers_.get() ?
       override_response_headers_ :
       transaction_->GetResponseInfo()->headers;
 }
 
 void URLRequestHttpJob::NotifyURLRequestDestroyed() {
   awaiting_callback_ = false;
 }
 
 }  // namespace net