Created a DownloadManager interface, for use in unit tests..

content/browser/download/download_file.cc

 // Copyright (c) 2011 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 "content/browser/download/download_file.h"
 
 #include <string>
 
 #include "base/file_util.h"
 #include "base/stringprintf.h"
 #include "content/browser/download/download_create_info.h"
 #include "content/browser/download/download_manager.h"
 #include "content/public/browser/browser_thread.h"
 
 namespace {
 
   // The maximum number of 'uniquified' files we will try to create.
 // This is used when the filename we're trying to download is already in use,
 // so we create a new unique filename by appending " (nnn)" before the
 // extension, where 1 <= nnn <= kMaxUniqueFiles.
 // Also used by code that cleans up said files.
 static const int kMaxUniqueFiles = 100;
 
 }
 
 DownloadFile::DownloadFile(const DownloadCreateInfo* info,
                            const DownloadRequestHandle& request_handle,
-                           DownloadManager* download_manager)
+                           DownloadManagerInterface* download_manager)
     : BaseFile(info->save_info.file_path,
                info->url(),
                info->referrer_url,
                info->received_bytes,
                info->save_info.file_stream),
       id_(info->download_id),
       request_handle_(request_handle),
       download_manager_(download_manager) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
 }
 
 DownloadFile::~DownloadFile() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
 }
 
 void DownloadFile::CancelDownloadRequest() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
   request_handle_.CancelRequest();
 }
 
-DownloadManager* DownloadFile::GetDownloadManager() {
+DownloadManagerInterface* DownloadFile::GetDownloadManager() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
   return download_manager_.get();
 }
 
 std::string DownloadFile::DebugString() const {
   return base::StringPrintf("{"
                             " id_ = " "%d"
                             " request_handle = %s"
                             " Base File = %s"
                             " }",
@@ skipping 44 matching lines @@
     new_path = FilePath(path);
     AppendNumberToPath(&new_path, count);
 
     if (!file_util::PathExists(new_path) &&
         !file_util::PathExists(AppendSuffixToPath(new_path, suffix)))
       return count;
   }
 
   return -1;
 }