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

chrome/browser/download/download_service.cc

Index: chrome/browser/download/download_service.cc
diff --git a/chrome/browser/download/download_service.cc b/chrome/browser/download/download_service.cc
index c5263be1da220a727c7cadd2a922e687e8a20c7d..113250b704f7ea957ec0161b1726dd1699f48e31 100644
--- a/chrome/browser/download/download_service.cc
+++ b/chrome/browser/download/download_service.cc
@@ -35,7 +35,7 @@ DownloadManager* DownloadService::GetDownloadManager() {
     // SetDownloadManagerDelegateForTesting.
     if (!manager_delegate_.get())
       manager_delegate_ = new ChromeDownloadManagerDelegate(profile_);
-    manager_ = new DownloadManager(
+    manager_ = new DownloadManagerImpl(
         manager_delegate_.get(),
         id_factory_.get(),
         g_browser_process->download_status_updater());
@@ -51,7 +51,7 @@ bool DownloadService::HasCreatedDownloadManager() {
 }
 
 int DownloadService::DownloadCount() const {
-  return download_manager_created_ ? manager_->in_progress_count() : 0;
+  return download_manager_created_ ? manager_->InProgressCount() : 0;
 }
 
 // static