[Download Notification] Show preview if downloaded file is image

chrome/browser/download/notification/download_notification_item.h

Index: chrome/browser/download/notification/download_notification_item.h
diff --git a/chrome/browser/download/notification/download_notification_item.h b/chrome/browser/download/notification/download_notification_item.h
index 76fb48b9e5a7e4c9d8b96d5f6850b98f4ec504be..4be50d2f6dcda278d9df8413545c379726081b4e 100644
--- a/chrome/browser/download/notification/download_notification_item.h
+++ b/chrome/browser/download/notification/download_notification_item.h
@@ -9,11 +9,13 @@
 
 #include "base/strings/string_number_conversions.h"
 #include "chrome/browser/download/download_commands.h"
+#include "chrome/browser/image_decoder.h"
 #include "chrome/browser/notifications/notification.h"
 #include "chrome/browser/notifications/notification_delegate.h"
 #include "chrome/browser/notifications/notification_test_util.h"
 #include "content/public/browser/download_item.h"
 #include "grit/theme_resources.h"
+#include "third_party/skia/include/core/SkBitmap.h"
 #include "ui/message_center/message_center.h"
 #include "ui/message_center/message_center_observer.h"
 
@@ -21,7 +23,8 @@ namespace test {
 class DownloadNotificationItemTest;
 }
 
-class DownloadNotificationItem : public content::DownloadItem::Observer {
+class DownloadNotificationItem : public content::DownloadItem::Observer,
+                                 public ImageDecoder::ImageRequest {
  public:
   class Delegate {
    public:
@@ -86,7 +89,16 @@ class DownloadNotificationItem : public content::DownloadItem::Observer {
   void CloseNotificationByUser();
   void CloseNotificationByNonUser();
   void UpdateNotificationData(NotificationUpdateType type);
-  void SetNotificationImage(int resource_id);
+
+  // Set icon of the notification.
+  void SetNotificationIcon(int resource_id);
+
+  // Set preview image of the notification. Must be called on IO thread.
+  void OnImageLoaded(std::string image_data);
+
+  // ImageDecoder::ImageRequest overrides:
+  void OnImageDecoded(const SkBitmap& decoded_image) override;
+  void OnDecodeImageFailed() override;
 
   NotificationUIManager* notification_ui_manager() const;
 
@@ -115,6 +127,11 @@ class DownloadNotificationItem : public content::DownloadItem::Observer {
   scoped_ptr<std::vector<DownloadCommands::Command>> button_actions_;
   Delegate* const delegate_;
 
+  // Whether the preview image been has set or not.
+  bool set_image_ = false;
+
+  base::WeakPtrFactory<DownloadNotificationItem> weak_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(DownloadNotificationItem);
 };