Refactor VR Shell Input. Locks input to click/scroll targets.

chrome/browser/android/vr_shell/textures/ui_texture.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_TEXTURES_UI_TEXTURE_H_
 #define CHROME_BROWSER_ANDROID_VR_SHELL_TEXTURES_UI_TEXTURE_H_
 
 #include <memory>
 
 #include "base/strings/string16.h"
 #include "ui/gfx/geometry/size.h"
 #include "ui/gfx/geometry/size_f.h"
 
 class SkCanvas;
 
 namespace gfx {
 class FontList;
 }  // namespace gfx
 
 namespace vr_shell {
 
 class UiTexture {
  public:
   UiTexture();
   virtual ~UiTexture();
 
   void DrawAndLayout(SkCanvas* canvas, const gfx::Size& texture_size);
   virtual gfx::Size GetPreferredTextureSize(int maximum_width) const = 0;
   virtual gfx::SizeF GetDrawnSize() const = 0;
+  // Returns true if the state changed.

[cjgrant, 2017/05/10 20:16:25]

Are you adding this here as a general purpose means of checking if some
arbitrary property changed?  I find it really confusing for the bit of help it's
offering.  It could just be a pair of get/set flags methods, and subclasses
could check and update as needed.  At a minimum, it should be renamed
UpdateDrawFlags() or something, as the texture is not actually being updated.

[mthiesse, 2017/05/10 21:09:08]

Changed to SetDrawFlags, missing getter was an oversight.

The purpose here is to make it easier to avoid re-drawing when not necessary.

We should flesh this out more in future CLs, as it's possible the state changes,
but the element still doesn't need to redraw.

+  bool Update(int draw_flags);
 
  protected:
   virtual void Draw(SkCanvas* canvas, const gfx::Size& texture_size) = 0;
 
   static bool IsRTL();
   static gfx::FontList GetDefaultFontList(int size);
   static gfx::FontList GetFontList(int size, base::string16 text);
+
+  int draw_flags_ = 0;
 };
 
 }  // namespace vr_shell
 
 #endif  // CHROME_BROWSER_ANDROID_VR_SHELL_TEXTURES_UI_TEXTURE_H_