Add a function to add extra headers from NavigationThrottle

content/browser/frame_host/navigation_handle_impl.h

 // Copyright 2015 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.
 
 #ifndef CONTENT_BROWSER_FRAME_HOST_NAVIGATION_HANDLE_IMPL_H_
 #define CONTENT_BROWSER_FRAME_HOST_NAVIGATION_HANDLE_IMPL_H_
 
 #include "content/public/browser/navigation_handle.h"
 
 #include "base/callback.h"
@@ skipping 94 matching lines @@
   bool is_transferring() const { return is_transferring_; }
   void set_is_transferring(bool is_transferring) {
     is_transferring_ = is_transferring;
   }
 
   // PlzNavigate
   ServiceWorkerNavigationHandle* service_worker_handle() const {
     return service_worker_handle_.get();
   }
 
-  typedef base::Callback<void(NavigationThrottle::ThrottleCheckResult)>
-      ThrottleChecksFinishedCallback;
+  using ExtraHeadersList = std::vector<std::pair<std::string, std::string> >;

[nasko, 2015/11/25 14:54:37]

nit: I think it is safe these days to have ">>" at the end without need for a
space. 

+  using ThrottleChecksFinishedCallback =
+      base::Callback<void(NavigationThrottle::ThrottleCheckResult,
+                          const ExtraHeadersList&)>;
+
+  // Adds an entry in the ExtraHeadersList. The extra header itself will be
+  // added to the request when the ThrottleChecksFinishedCallback will be run.
+  void AddExtraHeader(const std::string& name, const std::string& value);
 
   // Called when the URLRequest will start in the network stack.  |callback|
   // will be called when all throttle checks have completed. This will allow
   // the caller to cancel the navigation or let it proceed.
   void WillStartRequest(bool is_post,
                         const Referrer& sanitized_referrer,
                         bool has_user_gesture,
                         ui::PageTransition transition,
                         bool is_external_protocol,
                         const ThrottleChecksFinishedCallback& callback);
@@ skipping 70 matching lines @@
 
   // The FrameTreeNode this navigation is happening in.
   FrameTreeNode* frame_tree_node_;
 
   // A list of Throttles registered for this navigation.
   ScopedVector<NavigationThrottle> throttles_;
 
   // The index of the next throttle to check.
   size_t next_index_;
 
+  // Passed back to the handler of the navigation request after the throttles
+  // checks have been performed.
+  ExtraHeadersList extra_headers_to_add_;
+
   // This callback will be run when all throttle checks have been performed.
   ThrottleChecksFinishedCallback complete_callback_;
 
   // PlzNavigate
   // Manages the lifetime of a pre-created ServiceWorkerProviderHost until a
   // corresponding ServiceWorkerNetworkProvider is created in the renderer.
   scoped_ptr<ServiceWorkerNavigationHandle> service_worker_handle_;
 
   DISALLOW_COPY_AND_ASSIGN(NavigationHandleImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_FRAME_HOST_NAVIGATION_HANDLE_IMPL_H_