[vr] Ensure that textured elements never draw with a dirty texture

chrome/browser/android/vr_shell/ui_elements/textured_element.h

 // Copyright 2017 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_ANDROID_VR_SHELL_UI_ELEMENTS_TEXTURED_ELEMENT_H_
 #define CHROME_BROWSER_ANDROID_VR_SHELL_UI_ELEMENTS_TEXTURED_ELEMENT_H_
 
 #include "base/macros.h"
 #include "chrome/browser/android/vr_shell/ui_elements/ui_element.h"
 #include "ui/gfx/geometry/size.h"
@@ skipping 12 matching lines @@
   // rendered exactly at the preferred width.
   explicit TexturedElement(int maximum_width);
   ~TexturedElement() override;
 
   void Initialize() final;
 
   // UiElement interface.
   void Render(UiElementRenderer* renderer,
               gfx::Transform view_proj_matrix) const final;
 
+  void OnBeginFrame(const base::TimeTicks& begin_frame_time) override;
+
  protected:
   virtual UiTexture* GetTexture() const = 0;
   virtual void UpdateTexture();
   virtual void UpdateElementSize();
 
  private:
   void Flush(SkSurface* surface);
   void OnSetMode() override;
 
   gfx::Size texture_size_;
   GLuint texture_handle_;
   int maximum_width_;
   bool initialized_ = false;
 
   DISALLOW_COPY_AND_ASSIGN(TexturedElement);
 };
 
 }  // namespace vr_shell
 
 #endif  // CHROME_BROWSER_ANDROID_VR_SHELL_UI_ELEMENTS_TEXTURED_ELEMENT_H_