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

chrome/browser/android/download/download_manager_service.h

Index: chrome/browser/android/download/download_manager_service.h
diff --git a/chrome/browser/android/download/download_manager_service.h b/chrome/browser/android/download/download_manager_service.h
index d585dd3ca15833b1288a79a197671f6069deadcf..e3ac41a632a6c9cdc03b57d8a0e95a841d4c5e11 100644
--- a/chrome/browser/android/download/download_manager_service.h
+++ b/chrome/browser/android/download/download_manager_service.h
@@ -11,7 +11,9 @@
 
 #include "base/android/scoped_java_ref.h"
 #include "base/callback.h"
+#include "base/files/file_path.h"
 #include "base/macros.h"
+#include "base/memory/singleton.h"
 #include "chrome/browser/android/download/download_controller.h"
 #include "chrome/browser/download/all_download_item_notifier.h"
 #include "chrome/browser/download/download_history.h"
@@ -35,10 +37,14 @@ class DownloadManagerService : public AllDownloadItemNotifier::Observer,
       content::DownloadItem* download,
       DownloadController::DownloadCancelReason reason);
 
-  DownloadManagerService(JNIEnv* env,
-                         jobject jobj);
+  static DownloadManagerService* GetInstance();
+
+  DownloadManagerService();
   ~DownloadManagerService() override;
 
+  // Called to Initialize this object.
+  void Init(JNIEnv* env, jobject obj);
+
   // Called to resume downloading the item that has GUID equal to
   // |jdownload_guid|..
   void ResumeDownload(JNIEnv* env,
@@ -78,6 +84,8 @@ class DownloadManagerService : public AllDownloadItemNotifier::Observer,
   void CheckForExternallyRemovedDownloads(JNIEnv* env,
                                           const JavaParamRef<jobject>& obj,
                                           bool is_off_the_record);
+  // Remove externally removed downloads from history.
+  void RemoveExternallyRemovedDownloads(const base::FilePath& path);

[Theresa, 2016/09/21 17:40:43]

Can this be something like RemoveDownloadsForPath()?

// Remove download items associated with |path| from downloads history.

[qinmin, 2016/09/21 21:20:29]

Done.

 
   // DownloadHistory::Observer methods.
   void OnHistoryQueryComplete() override;
@@ -95,6 +103,7 @@ class DownloadManagerService : public AllDownloadItemNotifier::Observer,
  private:
   // For testing.
   friend class DownloadManagerServiceTest;
+  friend struct base::DefaultSingletonTraits<DownloadManagerService>;
 
   // Helper function to start the download resumption.
   void ResumeDownloadInternal(const std::string& download_guid,