Fire a notification in Windows 8 metro chrome which informs the user about a completed download. Th…

chrome/browser/download/download_completion_observer_win.cc

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chrome/browser/download/download_completion_observer_win.h"
+
+#include <string>
+
+#include "base/logging.h"
+#include "base/string_number_conversions.h"
+#include "base/win/metro.h"
+#include "googleurl/src/gurl.h"
+#include "grit/generated_resources.h"
+#include "ui/base/l10n/l10n_util.h"
+
+using content::DownloadItem;
+using content::DownloadManager;
+
+static const char kDownloadNotificationPrefix[] = "DownloadNotification";
+int g_next_notification_id = 0;
+
+void DownloadCompletionObserver::Initialize(DownloadManager* manager) {
+  manager->AddObserver(this);
+}
+
+void DownloadCompletionObserver::OnDownloadCreated(DownloadManager* manager,
+                                                   DownloadItem* item) {
+  item->AddObserver(this);

[asanka, 2012/08/07 17:31:58]

Only add an observer if item->IsInProgress() is true since those are the
downloads you are interested in.

Note that OnDownloadCreated() is called for each download item in history when
the history DB is being read. item->IsInProgress() will be false for history
downloads.

[ananta, 2012/08/07 18:08:28]

Done.

+}
+
+void DownloadCompletionObserver::ManagerGoingDown(DownloadManager* manager) {
+  manager->RemoveObserver(this);
+}
+
+void DownloadCompletionObserver::OnDownloadUpdated(DownloadItem* download) {
+  if (!base::win::IsMetroProcess())
+    return;
+

[asanka, 2012/08/07 17:31:58]

It is possible that the user has already marked the download to be opened upon
completion (item->GetOpenWhenComplete() is true), or it could be of a file type
that the user wants to open by default (item->ShouldOpenFileBasedOnExtension()
is true). I think you don't want to show notifications in those cases.

Also, ignore downloads that are temporary (item->IsTemporary() is true). Those
may not be meant to be handed over to the user as-is after the download
completes.

In addition, ignore downloads that have already been opened by the time it is
marked as COMPLETE (item->GetAutoOpened() is true). Currently this happens for
extension downloads.

Note that all of the above predicates should be checked after the download is in
the COMPLETE state.

[ananta, 2012/08/07 18:08:28]

Done.

+  if (download->GetState() == DownloadItem::COMPLETE) {
+    // In Windows 8 metro mode display a metro style notification which informs
+    // the user that the download is complete.
+    HMODULE metro = base::win::GetMetroModule();
+    base::win::MetroNotification display_notification =
+        reinterpret_cast< base::win::MetroNotification>(
+            ::GetProcAddress(metro, "DisplayNotification"));
+    DCHECK(display_notification);
+    if (display_notification) {
+      string16 title = l10n_util::GetStringUTF16(
+          IDS_METRO_DOWNLOAD_COMPLETE_NOTIFICATION_TITLE);
+      string16 body = l10n_util::GetStringUTF16(
+          IDS_METRO_DOWNLOAD_COMPLETE_NOTIFICATION);
+
+      // Dummy notification id. Every metro style notification needs a unique
+      // notification id.
+      std::string notification_id = kDownloadNotificationPrefix;
+      notification_id += base::IntToString(g_next_notification_id++);
+
+      display_notification(download->GetURL().spec().c_str(),
+                            "",
+                            title.c_str(),
+                            body.c_str(),
+                            L"",
+                            notification_id.c_str());
+    }

[asanka, 2012/08/07 17:31:58]

I suggest removing the observer when any of the terminal states are hit:
COMPLETE, INTERRUPTED, CANCELLED and also REMOVING. You are only interested in
the the transition from IN_PROGRESS -> COMPLETE.

This also implicitly deals with the possibility of getting another
OnDownloadUpdated() while the download is in the COMPLETE state. Currently that
would trigger a second notification.

[ananta, 2012/08/07 18:08:28]

Done.

+  } else if (download->GetState() == DownloadItem::REMOVING) {
+    download->RemoveObserver(this);
+  }
+}