Add Network.setSendRequestIdHeader and use it in headless

chrome/browser/devtools/devtools_network_transaction.h

 // Copyright 2014 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 CHROME_BROWSER_DEVTOOLS_DEVTOOLS_NETWORK_TRANSACTION_H_
 #define CHROME_BROWSER_DEVTOOLS_DEVTOOLS_NETWORK_TRANSACTION_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 28 matching lines @@
 
 // DevToolsNetworkTransaction is a wrapper for network transaction. All
 // HttpTransaction methods are proxied to real transaction, but |callback|
 // parameter is saved and replaced with proxy callback. Fail method should be
 // used to simulate network outage. It runs saved callback (if any) with
 // net::ERR_INTERNET_DISCONNECTED result value.
 class DevToolsNetworkTransaction
     : public net::HttpTransaction {
  public:
   static const char kDevToolsEmulateNetworkConditionsClientId[];
+  static const char kDevToolsRequestId[];
 
   DevToolsNetworkTransaction(
       DevToolsNetworkController* controller,
       std::unique_ptr<net::HttpTransaction> network_transaction);
 
   ~DevToolsNetworkTransaction() override;
 
   // HttpTransaction methods:
   int Start(const net::HttpRequestInfo* request,
             const net::CompletionCallback& callback,
@@ skipping 65 matching lines @@
 
   const net::HttpRequestInfo* request_;
 
   // True if Fail was already invoked.
   bool failed_;
 
   DISALLOW_COPY_AND_ASSIGN(DevToolsNetworkTransaction);
 };
 
 #endif  // CHROME_BROWSER_DEVTOOLS_DEVTOOLS_NETWORK_TRANSACTION_H_