Adds additional_client_area to client area

ui/views/mus/desktop_window_tree_host_mus.h

Index: ui/views/mus/desktop_window_tree_host_mus.h
diff --git a/ui/views/mus/desktop_window_tree_host_mus.h b/ui/views/mus/desktop_window_tree_host_mus.h
index 6603cf3dedc67b657e041df3b3518129f66a4353..562eb0a25b448b4c38a594e1c0ab84eb82132cb9 100644
--- a/ui/views/mus/desktop_window_tree_host_mus.h
+++ b/ui/views/mus/desktop_window_tree_host_mus.h
@@ -37,6 +37,11 @@ class VIEWS_MUS_EXPORT DesktopWindowTreeHostMus
   // Called when the window was deleted on the server.
   void ServerDestroyedWindow() { CloseNow(); }
 
+  // Controls whether the client area is automatically updated as necessary.
+  void set_auto_update_client_area(bool value) {
+    auto_update_client_area_ = value;
+  }
+
  private:
   bool IsDocked() const;
 
@@ -48,6 +53,9 @@ class VIEWS_MUS_EXPORT DesktopWindowTreeHostMus
 
   void SetBoundsInDIP(const gfx::Rect& bounds_in_dip);
 
+  // Returns true if the client area should be set on this.
+  bool ShouldSendClientAreaToServer() const;
+
   // DesktopWindowTreeHost:
   void Init(aura::Window* content_window,
             const Widget::InitParams& params) override;
@@ -142,6 +150,8 @@ class VIEWS_MUS_EXPORT DesktopWindowTreeHostMus
 
   std::unique_ptr<wm::CursorManager> cursor_manager_;
 
+  bool auto_update_client_area_ = true;
+
   // Used so that Close() isn't immediate.
   base::WeakPtrFactory<DesktopWindowTreeHostMus> close_widget_factory_;