Cleanup parameter passing issues in content/browser/download

content/browser/download/mock_download_manager.cc

Index: content/browser/download/mock_download_manager.cc
diff --git a/content/browser/download/mock_download_manager.cc b/content/browser/download/mock_download_manager.cc
index b5f71421c46fe3a58b3f0ace4a237865ce37d42c..575f3426070b627088af64197d04833e57871fd6 100644
--- a/content/browser/download/mock_download_manager.cc
+++ b/content/browser/download/mock_download_manager.cc
@@ -55,7 +55,7 @@ void MockDownloadManager::StartDownload(int32 id) {
 void MockDownloadManager::UpdateDownload(int32 download_id,
                                          int64 bytes_so_far,
                                          int64 bytes_per_sec,
-                                         std::string hash_state) {
+                                         const std::string& hash_state) {
 }
 
 void MockDownloadManager::OnResponseCompleted(int32 download_id, int64 size,
@@ -67,7 +67,7 @@ void MockDownloadManager::CancelDownload(int32 download_id) {
 
 void MockDownloadManager::OnDownloadInterrupted(int32 download_id,
                                                 int64 size,
-                                                std::string hash_state,
+                                                const std::string& hash_state,
                                                 InterruptReason reason) {
 }