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

content/browser/download/download_manager.cc

Index: content/browser/download/download_manager.cc
diff --git a/content/browser/download/download_manager.cc b/content/browser/download/download_manager.cc
index 5cdf0065083262566f8ca7e91ae9278dbcc77af0..dffa8e04877a762816d3f6e01e313fa321f31018 100644
--- a/content/browser/download/download_manager.cc
+++ b/content/browser/download/download_manager.cc
@@ -313,6 +313,14 @@ void DownloadManager::RestartDownload(
   }
 }
 
+content::BrowserContext* DownloadManager::BrowserContext() {
+  return browser_context_;
+}
+
+FilePath DownloadManager::LastDownloadPath() {
+  return last_download_path_;
+}
+
 void DownloadManager::CreateDownloadItem(
     DownloadCreateInfo* info, const DownloadRequestHandle& request_handle) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
@@ -605,6 +613,10 @@ void DownloadManager::RemoveFromActiveList(DownloadItem* download) {
   }
 }
 
+content::DownloadManagerDelegate* DownloadManager::delegate() const {
+  return delegate_;
+}
+
 void DownloadManager::SetDownloadManagerDelegate(
     content::DownloadManagerDelegate* delegate) {
   delegate_ = delegate;
@@ -928,6 +940,10 @@ void DownloadManager::ShowDownloadInBrowser(DownloadItem* download) {
     content->OnStartDownload(download);
 }
 
+int DownloadManager::InProgressCount() const {
+  return static_cast<int>(in_progress_.size());
+}
+
 // Clears the last download path, used to initialize "save as" dialogs.
 void DownloadManager::ClearLastDownloadPath() {
   last_download_path_ = FilePath();
@@ -1077,3 +1093,7 @@ void DownloadManager::MarkDownloadOpened(DownloadItem* download) {
   }
   download_stats::RecordOpensOutstanding(num_unopened);
 }
+
+void DownloadManager::SetFileManager(DownloadFileManager* file_manager) {
+  file_manager_ = file_manager;
+}