Linux UI: Dynamically respond to changes in the scale factor

ui/views/widget/desktop_aura/desktop_window_tree_host_x11.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_WIDGET_DESKTOP_AURA_DESKTOP_WINDOW_TREE_HOST_X11_H_
 #define UI_VIEWS_WIDGET_DESKTOP_AURA_DESKTOP_WINDOW_TREE_HOST_X11_H_
 
 #include <stddef.h>
 #include <stdint.h>
 #include <X11/extensions/shape.h>
 #include <X11/Xlib.h>
 #include <X11/Xutil.h>
 
 #include "base/cancelable_callback.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
 #include "ui/aura/scoped_window_targeter.h"
 #include "ui/aura/window_tree_host.h"
 #include "ui/base/cursor/cursor_loader_x11.h"
+#include "ui/display/display_observer.h"
 #include "ui/events/platform/platform_event_dispatcher.h"
 #include "ui/gfx/geometry/insets.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/geometry/size.h"
 #include "ui/views/views_export.h"
 #include "ui/views/widget/desktop_aura/desktop_window_tree_host.h"
 
 namespace gfx {
 class ImageSkia;
 class ImageSkiaRep;
 }
 
 namespace ui {
 class EventHandler;
 class XScopedEventSelector;
 }
 
 namespace views {
 class DesktopDragDropClientAuraX11;
 class DesktopWindowTreeHostObserverX11;
 class NonClientFrameView;
 class X11DesktopWindowMoveClient;
 
 class VIEWS_EXPORT DesktopWindowTreeHostX11
     : public DesktopWindowTreeHost,
       public aura::WindowTreeHost,
-      public ui::PlatformEventDispatcher {
+      public ui::PlatformEventDispatcher,
+      public display::DisplayObserver {
  public:
   DesktopWindowTreeHostX11(
       internal::NativeWidgetDelegate* native_widget_delegate,
       DesktopNativeWidgetAura* desktop_native_widget_aura);
   ~DesktopWindowTreeHostX11() override;
 
   // A way of converting an X11 |xid| host window into a |content_window_|.
   static aura::Window* GetContentWindowForXID(XID xid);
 
   // A way of converting an X11 |xid| host window into this object.
@@ skipping 104 matching lines @@
   gfx::Rect GetBoundsInPixels() const override;
   void SetBoundsInPixels(const gfx::Rect& requested_bounds_in_pixels) override;
   gfx::Point GetLocationOnScreenInPixels() const override;
   void SetCapture() override;
   void ReleaseCapture() override;
   void SetCursorNative(gfx::NativeCursor cursor) override;
   void MoveCursorToScreenLocationInPixels(
       const gfx::Point& location_in_pixels) override;
   void OnCursorVisibilityChangedNative(bool show) override;
 
+  // Overridden from display::DisplayObserver:
+  void OnDisplayAdded(const display::Display& new_display) override;
+  void OnDisplayRemoved(const display::Display& old_display) override;
+  void OnDisplayMetricsChanged(const display::Display& display,
+                               uint32_t changed_metrics) override;
+
  private:
   friend class DesktopWindowTreeHostX11HighDPITest;
   // Initializes our X11 surface to draw on. This method performs all
   // initialization related to talking to the X11 server.
   void InitX11Window(const Widget::InitParams& params);
 
   // Creates an aura::WindowEventDispatcher to contain the |content_window|,
   // along with all aura client objects that direct behavior.
   aura::WindowEventDispatcher* InitDispatcher(const Widget::InitParams& params);
 
@@ skipping 243 matching lines @@
 
   base::WeakPtrFactory<DesktopWindowTreeHostX11> close_widget_factory_;
   base::WeakPtrFactory<DesktopWindowTreeHostX11> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(DesktopWindowTreeHostX11);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_WIDGET_DESKTOP_AURA_DESKTOP_WINDOW_TREE_HOST_X11_H_