Remove use of WS_EX_COMPOSITED for translucent windows.

ui/views/win/hwnd_message_handler.h

Index: ui/views/win/hwnd_message_handler.h
diff --git a/ui/views/win/hwnd_message_handler.h b/ui/views/win/hwnd_message_handler.h
index f56a7ca05927ae0f5c947899aaeb522ca9db6667..5018970b001623ea6f5502b608e7acdc78d5cf37 100644
--- a/ui/views/win/hwnd_message_handler.h
+++ b/ui/views/win/hwnd_message_handler.h
@@ -213,6 +213,11 @@ class VIEWS_EXPORT HWNDMessageHandler :
   // 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 };
@@ -706,6 +711,10 @@ class VIEWS_EXPORT HWNDMessageHandler :
   // 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.