Add new UMA stats for parallelizable download

content/browser/download/mock_download_file.cc

Index: content/browser/download/mock_download_file.cc
diff --git a/content/browser/download/mock_download_file.cc b/content/browser/download/mock_download_file.cc
index 36282d51b4dcb7c20a5f80cbaf6721661670067a..14bb474b3b01bc9540023c77fb8eee677e7671f3 100644
--- a/content/browser/download/mock_download_file.cc
+++ b/content/browser/download/mock_download_file.cc
@@ -12,7 +12,8 @@ namespace content {
 namespace {
 
 void SuccessRun(const DownloadFile::InitializeCallback& callback,
-                const DownloadItem::ReceivedSlices& received_slices) {
+                const DownloadItem::ReceivedSlices& received_slices,
+                bool is_parallelizable) {
   callback.Run(DOWNLOAD_INTERRUPT_REASON_NONE);
 }
 
@@ -21,7 +22,8 @@ void SuccessRun(const DownloadFile::InitializeCallback& callback,
 MockDownloadFile::MockDownloadFile() {
   // This is here because |Initialize()| is normally called right after
   // construction.
-  ON_CALL(*this, Initialize(_, _)).WillByDefault(::testing::Invoke(SuccessRun));
+  ON_CALL(*this, Initialize(_, _, _))
+      .WillByDefault(::testing::Invoke(SuccessRun));
 }
 
 MockDownloadFile::~MockDownloadFile() {