Clear the cached avatar button offset when the DPI scaling changes

chrome/browser/ui/views/frame/minimize_button_metrics_win.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 CHROME_BROWSER_UI_VIEWS_FRAME_MINIMIZE_BUTTON_METRICS_WIN_H_
 #define CHROME_BROWSER_UI_VIEWS_FRAME_MINIMIZE_BUTTON_METRICS_WIN_H_
 
 #include <windows.h>
 
 #include "base/macros.h"
@@ skipping 14 matching lines @@
 
   // Obtain the X offset of the native minimize button. Since Windows can lie
   // to us if we call this at the wrong moment, this might come from a cached
   // value rather than read when called.
   int GetMinimizeButtonOffsetX() const;
 
   // Must be called when hwnd_ is activated to update the minimize button
   // position cache.
   void OnHWNDActivated();
 
+  // Must be called when WM_DPICHANGED message is received.
+  void OnDpiChanged();
+
  private:
   // Gets the value for GetMinimizeButtonOffsetX(), caching if found.
   int GetAndCacheMinimizeButtonOffsetX() const;
 
   int GetButtonBoundsPositionOffset(const RECT& button_bounds,
                                     const RECT& window_bounds) const;
 
   int GetMinimizeButtonOffsetForWindow() const;
 
   HWND hwnd_;
@@ skipping 10 matching lines @@
   // DWMWA_CAPTION_BUTTON_BOUNDS and WM_GETTITLEBARINFOEX
   static int button_bounds_position_offset_;
 
   // Has OnHWNDActivated() been invoked?
   bool was_activated_;
 
   DISALLOW_COPY_AND_ASSIGN(MinimizeButtonMetrics);
 };
 
 #endif  // CHROME_BROWSER_UI_VIEWS_FRAME_MINIMIZE_BUTTON_METRICS_WIN_H_