Let SimpleDownloadManagerCoordinator inform observers when a download is created

This CL adds a new observer method for that.
We don't really need the OnManagerGoingDown() method since the coordinator
can live longer

BUG=942770

Change-Id: Ieaf3e13facc52022f2ec35c8cdf0f3a7c0170fd5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1546259
Commit-Queue: Min Qin <qinmin@chromium.org>
Reviewed-by: Shakti Sahu <shaktisahu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#646565}

components/download/internal/common/simple_download_manager.cc

@@ -10,6 +10,14 @@ SimpleDownloadManager::SimpleDownloadManager() {}
 
 SimpleDownloadManager::~SimpleDownloadManager() = default;
 
+void SimpleDownloadManager::AddObserver(Observer* observer) {
+  simple_download_manager_observers_.AddObserver(observer);
+}
+
+void SimpleDownloadManager::RemoveObserver(Observer* observer) {
+  simple_download_manager_observers_.RemoveObserver(observer);
+}
+
 void SimpleDownloadManager::OnInitialized() {
   initialized_ = true;
   for (auto& callback : std::move(on_initialized_callbacks_))

components/download/internal/common/simple_download_manager_coordinator.cc

@@ -17,13 +17,19 @@ SimpleDownloadManagerCoordinator::SimpleDownloadManagerCoordinator()
       initialized_(false),
       weak_factory_(this) {}
 
-SimpleDownloadManagerCoordinator::~SimpleDownloadManagerCoordinator() = default;
+SimpleDownloadManagerCoordinator::~SimpleDownloadManagerCoordinator() {
+  for (auto& observer : observers_)
+    observer.OnManagerGoingDown();
+}
 
 void SimpleDownloadManagerCoordinator::SetSimpleDownloadManager(
     SimpleDownloadManager* simple_download_manager,
     bool manages_all_history_downloads) {
   DCHECK(simple_download_manager_);
+  if (simple_download_manager_)
+    simple_download_manager_->RemoveObserver(this);
   simple_download_manager_ = simple_download_manager;
+  simple_download_manager_->AddObserver(this);
   simple_download_manager_->NotifyWhenInitialized(base::BindOnce(
       &SimpleDownloadManagerCoordinator::OnManagerInitialized,
       weak_factory_.GetWeakPtr(), manages_all_history_downloads));
@@ -63,4 +69,13 @@ void SimpleDownloadManagerCoordinator::OnManagerInitialized(
     observer.OnDownloadsInitialized(!has_all_history_downloads);
 }
 
+void SimpleDownloadManagerCoordinator::OnManagerGoingDown() {
+  simple_download_manager_ = nullptr;
+}
+
+void SimpleDownloadManagerCoordinator::OnDownloadCreated(DownloadItem* item) {
+  for (auto& observer : observers_)
+    observer.OnDownloadCreated(item);
+}
+
 }  // namespace download

components/download/public/common/simple_download_manager.h

@@ -9,6 +9,7 @@
 #include <string>
 #include <vector>
 
+#include "base/observer_list.h"
 #include "components/download/public/common/download_export.h"
 #include "components/download/public/common/download_url_parameters.h"
 
@@ -25,12 +26,8 @@ class COMPONENTS_DOWNLOAD_EXPORT SimpleDownloadManager {
     Observer() = default;
     virtual ~Observer() = default;
 
-    virtual void OnDownloadsInitialized(bool active_downloads_only) {}
     virtual void OnManagerGoingDown() {}
     virtual void OnDownloadCreated(DownloadItem* item) {}
-    virtual void OnDownloadUpdated(DownloadItem* item) {}
-    virtual void OnDownloadOpened(DownloadItem* item) {}
-    virtual void OnDownloadRemoved(DownloadItem* item) {}
 
    private:
     DISALLOW_COPY_AND_ASSIGN(Observer);
@@ -39,6 +36,9 @@ class COMPONENTS_DOWNLOAD_EXPORT SimpleDownloadManager {
   SimpleDownloadManager();
   virtual ~SimpleDownloadManager();
 
+  void AddObserver(Observer* observer);
+  void RemoveObserver(Observer* observer);
+
   // Calls the callback if this object becomes initialized.
   void NotifyWhenInitialized(base::OnceClosure callback);
 
@@ -62,6 +62,9 @@ class COMPONENTS_DOWNLOAD_EXPORT SimpleDownloadManager {
   // Whether this object is initialized.
   bool initialized_ = false;
 
+  // Observers that want to be notified of changes to the set of downloads.
+  base::ObserverList<Observer>::Unchecked simple_download_manager_observers_;
+
  private:
   // Callbacks to call once this object is initialized.
   std::vector<base::OnceClosure> on_initialized_callbacks_;

components/download/public/common/simple_download_manager_coordinator.h

@@ -13,29 +13,32 @@
 #include "base/observer_list.h"
 #include "components/download/public/common/download_export.h"
 #include "components/download/public/common/download_url_parameters.h"
+#include "components/download/public/common/simple_download_manager.h"
 
 namespace download {
 
 class DownloadItem;
-class SimpleDownloadManager;
 
 // This object allows swapping between different SimppleDownloadManager
 // instances so that callers don't need to know about the swap.
-class COMPONENTS_DOWNLOAD_EXPORT SimpleDownloadManagerCoordinator {
+class COMPONENTS_DOWNLOAD_EXPORT SimpleDownloadManagerCoordinator
+    : SimpleDownloadManager::Observer {
  public:
   class Observer {
    public:
     Observer() = default;
     virtual ~Observer() = default;
 
+    virtual void OnManagerGoingDown() {}
     virtual void OnDownloadsInitialized(bool active_downloads_only) {}
+    virtual void OnDownloadCreated(DownloadItem* item) {}
 
    private:
     DISALLOW_COPY_AND_ASSIGN(Observer);
   };
 
   SimpleDownloadManagerCoordinator();
-  ~SimpleDownloadManagerCoordinator();
+  ~SimpleDownloadManagerCoordinator() override;
 
   void AddObserver(Observer* observer);
   void RemoveObserver(Observer* observer);
@@ -58,6 +61,10 @@ class COMPONENTS_DOWNLOAD_EXPORT SimpleDownloadManagerCoordinator {
   bool has_all_history_downloads() const { return has_all_history_downloads_; }
 
  private:
+  // SimpleDownloadManager::Observer implementation.
+  void OnManagerGoingDown() override;
+  void OnDownloadCreated(DownloadItem* item) override;
+
   // Called when |simple_download_manager_| is initialized.
   void OnManagerInitialized(bool has_all_history_downloads);