DCHECK that jstring to C++ string conversions don't pass in null.

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 "base/android/jni_android.h"
 #include "base/android/jni_array.h"
 #include "base/android/jni_string.h"
 #include "chrome/browser/ui/tab_contents/core_tab_helper.h"
 #include "components/data_reduction_proxy/core/common/data_reduction_proxy_headers.h"
 #include "content/public/browser/android/content_view_core.h"
 #include "content/public/browser/android/download_controller_android.h"
 #include "content/public/browser/render_frame_host.h"
 #include "content/public/browser/render_process_host.h"
 #include "content/public/common/context_menu_params.h"
 #include "jni/ContextMenuHelper_jni.h"
 #include "jni/ContextMenuParams_jni.h"
 #include "ui/android/window_android.h"
 #include "ui/gfx/geometry/point.h"
 
 using base::android::ConvertJavaStringToUTF8;
 using base::android::ConvertUTF8ToJavaString;
 using base::android::ConvertUTF16ToJavaString;
 
 DEFINE_WEB_CONTENTS_USER_DATA_KEY(ContextMenuHelper);
 
-namespace {
-
 const int kShareImageMaxWidth = 2048;
 const int kShareImageMaxHeight = 2048;
 
-}  // namespace
+const char kDataReductionProxyPassthroughHeader[] =

[Miguel Garcia, 2016/03/30 14:30:12]

can you at least add a comment saying that the java version is in
chrome/android/java/src/org/chromium/chrome/browser/contextmenu/ContextMenuHelper.java
and should be kept in sync?

[Bernhard Bauer, 2016/03/30 14:43:44]

It's gone from there. That value was only used to pass it to C++, so I moved the
whole thing here.

+    "Chrome-Proxy: pass-through\r\n";
 
 ContextMenuHelper::ContextMenuHelper(content::WebContents* web_contents)
     : web_contents_(web_contents) {
   JNIEnv* env = base::android::AttachCurrentThread();
   java_obj_.Reset(
       env,
       Java_ContextMenuHelper_create(env, reinterpret_cast<long>(this)).obj());
   DCHECK(!java_obj_.is_null());
 }
 
@@ skipping 55 matching lines @@
           ConvertUTF8ToJavaString(env, params.unfiltered_link_url.spec()).obj(),
           ConvertUTF8ToJavaString(env, params.src_url.spec()).obj(),
           ConvertUTF16ToJavaString(env, params.title_text).obj(),
           image_was_fetched_lo_fi,
           ConvertUTF8ToJavaString(env, sanitizedReferrer.spec()).obj(),
           params.referrer_policy);
 
   return jmenu_info;
 }
 
-void ContextMenuHelper::OnStartDownload(JNIEnv* env,
-                                        const JavaParamRef<jobject>& obj,
-                                        jboolean jis_link,
-                                        const JavaParamRef<jstring>& jheaders) {
-  std::string headers(ConvertJavaStringToUTF8(env, jheaders));
+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;
+
   content::DownloadControllerAndroid::Get()->StartContextMenuDownload(
       context_menu_params_,
       web_contents_,
       jis_link,
       headers);
 }
 
 void ContextMenuHelper::SearchForImage(JNIEnv* env,
                                        const JavaParamRef<jobject>& obj) {
   content::RenderFrameHost* render_frame_host =
@@ skipping 44 matching lines @@
       env,
       java_obj_.obj(),
       jwindow_android.obj(),
       j_bytes.obj());
 }
 
 bool RegisterContextMenuHelper(JNIEnv* env) {
   return RegisterNativesImpl(env) &&
          ContextMenuParamsAndroid::RegisterNativesImpl(env);
 }