Remove use of WS_EX_COMPOSITED for translucent windows.

ui/views/win/hwnd_message_handler.h

 // 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.
 
 #ifndef UI_VIEWS_WIN_HWND_MESSAGE_HANDLER_H_
 #define UI_VIEWS_WIN_HWND_MESSAGE_HANDLER_H_
 
 #include <windows.h>
 
 #include <stddef.h>
@@ skipping 195 matching lines @@
 
   void SetFullscreen(bool fullscreen);
 
   // Updates the window style to reflect whether it can be resized or maximized.
   void SizeConstraintsChanged();
 
   // Returns true if content is rendered to a child window instead of directly
   // to this window.
   bool HasChildRenderingWindow();
 
+  void set_is_translucent(bool is_translucent) {
+    is_translucent_ = is_translucent;
+  }
+  bool is_translucent() const { return is_translucent_; }
+
  private:
   typedef std::set<DWORD> TouchIDs;
   enum class DwmFrameState { OFF, ON };
 
   // Overridden from WindowImpl:
   HICON GetDefaultWindowIcon() const override;
   HICON GetSmallWindowIcon() const override;
   LRESULT OnWndProc(UINT message, WPARAM w_param, LPARAM l_param) override;
 
   // Overridden from WindowEventTarget
@@ skipping 473 matching lines @@
   gfx::Point caption_left_button_click_pos_;
 
   // Set to true if the left mouse button has been pressed on the caption.
   // Defaults to false.
   bool left_button_down_on_caption_;
 
   // Set to true if the window is a background fullscreen window, i.e a
   // fullscreen window which lost activation. Defaults to false.
   bool background_fullscreen_hack_;
 
+  // True if the window should have no border and its contents should be
+  // partially or fully transparent.
+  bool is_translucent_ = false;
+
   // This is a map of the HMONITOR to full screeen window instance. It is safe
   // to keep a raw pointer to the HWNDMessageHandler instance as we track the
   // window destruction and ensure that the map is cleaned up.
   using FullscreenWindowMonitorMap = std::map<HMONITOR, HWNDMessageHandler*>;
   static base::LazyInstance<FullscreenWindowMonitorMap>::DestructorAtExit
       fullscreen_monitor_map_;
 
   // The WeakPtrFactories below must occur last in the class definition so they
   // get destroyed last.
 
   // The factory used to lookup appbar autohide edges.
   base::WeakPtrFactory<HWNDMessageHandler> autohide_factory_;
 
   // The factory used with BEGIN_SAFE_MSG_MAP_EX.
   base::WeakPtrFactory<HWNDMessageHandler> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(HWNDMessageHandler);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_WIN_HWND_MESSAGE_HANDLER_H_