Centralize the Data Reduction Proxy pass through header

chrome/browser/ui/android/context_menu_helper.cc

 // Copyright 2013 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 "chrome/browser/ui/android/context_menu_helper.h"
 
 #include <stdint.h>
 
 #include <vector>
 
@@ skipping 18 matching lines @@
 #include "ui/gfx/geometry/point.h"
 #include "ui/gfx/geometry/size.h"
 
 using base::android::ConvertJavaStringToUTF8;
 using base::android::ConvertUTF8ToJavaString;
 using base::android::ConvertUTF16ToJavaString;
 using base::android::JavaParamRef;
 
 DEFINE_WEB_CONTENTS_USER_DATA_KEY(ContextMenuHelper);
 
-const char kDataReductionProxyPassthroughHeader[] =
-    "Chrome-Proxy-Accept-Transform: identity\r\n";
-
 namespace {
 
 class ContextMenuHelperImageRequest : public ImageDecoder::ImageRequest {
  public:
   static void Start(const base::android::JavaRef<jobject>& jcallback,
                     const std::vector<uint8_t>& thumbnail_data) {
     ContextMenuHelperImageRequest* request =
         new ContextMenuHelperImageRequest(jcallback);
     ImageDecoder::Start(request, thumbnail_data);
   }
@@ skipping 125 matching lines @@
   return web_contents_->GetJavaWebContents();
 }
 
 void ContextMenuHelper::OnStartDownload(
     JNIEnv* env,
     const JavaParamRef<jobject>& obj,
     jboolean jis_link,
     jboolean jis_data_reduction_proxy_enabled) {
   std::string headers;
   if (jis_data_reduction_proxy_enabled)
-    headers = kDataReductionProxyPassthroughHeader;
+    headers = data_reduction_proxy::chrome_proxy_pass_through_header();
 
   DownloadControllerBase::Get()->StartContextMenuDownload(
       context_menu_params_,
       web_contents_,
       jis_link,
       headers);
 }
 
 void ContextMenuHelper::SearchForImage(JNIEnv* env,
                                        const JavaParamRef<jobject>& obj) {
@@ skipping 41 matching lines @@
   auto* thumbnail_capturer_proxy = thumbnail_capturer.get();
   thumbnail_capturer_proxy->RequestThumbnailForContextNode(
       0, gfx::Size(max_dimen_px, max_dimen_px),
       base::Bind(retrieve_callback, base::Passed(&thumbnail_capturer),
                  base::android::ScopedJavaGlobalRef<jobject>(env, jcallback)));
 }
 
 bool RegisterContextMenuHelper(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }