Add flag to specify if explicitly requested download is from web.

chrome/browser/download/download_extension_api.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 "chrome/browser/download/download_extension_api.h"
 
 #include <algorithm>
 #include <cctype>
 #include <iterator>
 #include <set>
@@ skipping 484 matching lines @@
     request->AppendBytesToUpload(iodata_->post_body.data(),
                                  iodata_->post_body.size());
   }
 
   // Prevent login prompts for 401/407 responses.
   request->set_load_flags(request->load_flags() |
                           net::LOAD_DO_NOT_PROMPT_FOR_LOGIN);
 
   net::Error error = iodata_->rdh->BeginDownload(
       request.Pass(),
+      false,  // is_content_initiated
       iodata_->resource_context,
       iodata_->render_process_host_id,
       iodata_->render_view_host_routing_id,
       false,  // prefer_cache
       save_info,
       base::Bind(&DownloadsDownloadFunction::OnStarted, this));
   iodata_.reset();
 
   if (error != net::OK) {
     BrowserThread::PostTask(
@@ skipping 559 matching lines @@
   ListValue args;
   args.Append(arg);
   std::string json_args;
   base::JSONWriter::Write(&args, &json_args);
   profile_->GetExtensionEventRouter()->DispatchEventToRenderers(
       event_name,
       json_args,
       profile_,
       GURL());
 }