Moves the notification icon out of the status area overflow.

chrome/browser/ui/views/message_center/tray_watcher_win.h

+// Copyright 2014 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.
+
+#ifndef CHROME_BROWSER_UI_VIEWS_MESSAGE_CENTER_TRAY_WATCHER_WIN_H_
+#define CHROME_BROWSER_UI_VIEWS_MESSAGE_CENTER_TRAY_WATCHER_WIN_H_
+
+#include "base/memory/scoped_ptr.h"
+#include "base/strings/string16.h"
+#include "base/threading/non_thread_safe.h"
+#include "base/win/iunknown_impl.h"
+#include "base/win/scoped_comptr.h"
+
+namespace message_center {
+
+// The known values for NOTIFYITEM's dwPreference member.
+enum NOTIFYITEM_PREFERENCE {
+  // In Windows UI: "Only show notifications."
+  PREFERENCE_SHOW_WHEN_ACTIVE = 0x00,

[Dmitry Titov, 2014/03/18 22:34:13]

that leading 0 is mysterious...

[dewittj, 2014/03/19 18:36:15]

Done.

+  // In Windows UI: "Hide icon and notifications."
+  PREFERENCE_SHOW_NEVER = 0x01,
+  // In Windows UI: "Show icon and notifications."
+  PREFERENCE_SHOW_ALWAYS = 0x02
+};
+
+const DWORD NOTIFYITEM_PREFERENCE_COUNT = 0x03;
+
+// NOTIFYITEM describes an entry in the taskbar's registry of status icons.
+// This structure outlives the process that creates the status item.

[Dmitry Titov, 2014/03/18 22:34:13]

This comment is unclear. This structure or the registry information passed into
Explorer using this structure outlives the process?

[dewittj, 2014/03/19 18:36:15]

Done.

+struct NOTIFYITEM {
+  PWSTR pszExeName;  // The file name of the creating executable.
+  PWSTR pszTip;  // The last hover-text value associated with this status item.
+  HICON hIcon;   // The icon associated with this status item.
+  HWND hWnd;     // The HWND associated with the status item.
+  DWORD dwPreference;  // Determines the behavior of the icon with respect to
+                       // the taskbar. Values taken from NOTIFYITEM_PREFERENCE.
+  UINT uID;  // The ID specified by the application.  (hWnd, uID) is unique.
+  GUID guidItem;  // The GUID specified by the application, alternative to uID.
+};
+
+// INotificationCB GUID
+[uuid("D782CCBA-AFB0-43F1-94DB-FDA3779EACCB")] interface INotificationCB
+    : public IUnknown {
+  STDMETHOD(Notify)(ULONG event, NOTIFYITEM* notify_item) = 0;
+};
+
+class TrayWatcherWin : public INotificationCB,
+                       public base::win::IUnknownImpl,
+                       public base::NonThreadSafe {
+ public:
+  explicit TrayWatcherWin(UINT icon_id, HWND window);

[Dmitry Titov, 2014/03/18 22:34:13]

no need to have 'explicit' with 2 params.

[dewittj, 2014/03/19 18:36:15]

Done.

+
+  // Creates an instance of TrayNotify, and ensures that it supports either

[Dmitry Titov, 2014/03/18 22:34:13]

The comment and the name of method seem to talk about different things.

[dewittj, 2014/03/19 18:36:15]

Done.

+  // ITrayNotify or ITrayNotifyWin8.  Returns true on success.
+  void EnsureTrayIconVisible();
+
+  // IUnknown.
+  STDMETHOD_(ULONG, AddRef)() OVERRIDE;
+  STDMETHOD_(ULONG, Release)() OVERRIDE;
+  STDMETHOD(QueryInterface)(REFIID, PVOID*)OVERRIDE;
+
+  // INotificationCB.
+  STDMETHOD(Notify)(ULONG, NOTIFYITEM*);
+
+  ~TrayWatcherWin();
+
+ private:
+  friend class TrayWatcherWinTest;
+
+  enum InterfaceVersion {
+    INTERFACE_VERSION_LEGACY = 0,
+    INTERFACE_VERSION_WIN8,
+    INTERFACE_VERSION_UNKNOWN
+  };
+
+  bool CreateTrayNotify();
+  scoped_ptr<NOTIFYITEM> RegisterCallback();
+
+  bool RegisterCallbackWin8();
+  bool RegisterCallbackLegacy();
+
+  void SendNotifyItemUpdate(scoped_ptr<NOTIFYITEM> notify_item);
+
+  scoped_ptr<NOTIFYITEM> notify_item_;
+
+  // Storing IUnknown since we will need to use different interfaces
+  // for different versions of Windows.
+  base::win::ScopedComPtr<IUnknown> tray_notify_;
+  InterfaceVersion interface_version_;
+
+  UINT icon_id_;
+  HWND window_;
+  base::string16 file_name_;
+};
+
+}  // namespace message_center
+#endif  // CHROME_BROWSER_UI_VIEWS_MESSAGE_CENTER_TRAY_WATCHER_WIN_H_