Ask download manager to remove a download if it is overwritten by another

chrome/browser/android/download/download_manager_service.cc

Index: chrome/browser/android/download/download_manager_service.cc
diff --git a/chrome/browser/android/download/download_manager_service.cc b/chrome/browser/android/download/download_manager_service.cc
index f00173594033be98ce8d3a58358bbd1f0e705993..92f45401d983ae518d48fbc6a1ebffc7b1d03e20 100644
--- a/chrome/browser/android/download/download_manager_service.cc
+++ b/chrome/browser/android/download/download_manager_service.cc
@@ -65,11 +65,15 @@ void DownloadManagerService::OnDownloadCanceled(
   DownloadController::RecordDownloadCancelReason(reason);
 }
 
+// static
+DownloadManagerService* DownloadManagerService::GetInstance() {
+  return base::Singleton<DownloadManagerService>::get();
+}
 
 static jlong Init(JNIEnv* env, const JavaParamRef<jobject>& jobj) {
   Profile* profile = ProfileManager::GetActiveUserProfile();
-  DownloadManagerService* service =
-      new DownloadManagerService(env, jobj);
+  DownloadManagerService* service = DownloadManagerService::GetInstance();
+  service->Init(env, jobj);
   DownloadService* download_service =
       DownloadServiceFactory::GetForBrowserContext(profile);
   DownloadHistory* history = download_service->GetDownloadHistory();
@@ -78,17 +82,20 @@ static jlong Init(JNIEnv* env, const JavaParamRef<jobject>& jobj) {
   return reinterpret_cast<intptr_t>(service);
 }
 
-DownloadManagerService::DownloadManagerService(
+DownloadManagerService::DownloadManagerService()
+    : is_history_query_complete_(false) {
+}
+
+DownloadManagerService::~DownloadManagerService() {}
+
+void DownloadManagerService::Init(
     JNIEnv* env,
-    jobject obj)
-    : java_ref_(env, obj),
-      is_history_query_complete_(false) {
+    jobject obj) {
+  java_ref_.Reset(env, obj);
   DownloadControllerBase::Get()->SetDefaultDownloadFileName(
       l10n_util::GetStringUTF8(IDS_DEFAULT_DOWNLOAD_FILENAME));
 }
 
-DownloadManagerService::~DownloadManagerService() {}
-
 void DownloadManagerService::ResumeDownload(
     JNIEnv* env,
     jobject obj,