Refactor GL surface format handling

ui/gl/gl_surface_format.h

+// Copyright (c) 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 UI_GL_GL_SURFACE_FORMAT_H_
+#define UI_GL_GL_SURFACE_FORMAT_H_
+
+namespace gl {
+
+class GLSurfaceFormat {
+ public:
+
+  // Minimum bit depth and format of surface.
+  enum SurfaceFormat {
+    SURFACE_ARGB8888,
+    SURFACE_RGB565,
+    SURFACE_OSMESA_BGRA,
+    SURFACE_OSMESA_RGBA,
+    SURFACE_SURFACELESS,
+  };
+
+  enum SurfacePixelLayout {
+    SURFACE_PIXEL_LAYOUT_DONT_CARE = -1,
+    SURFACE_PIXEL_LAYOUT_BGRA,
+    SURFACE_PIXEL_LAYOUT_RGBA,
+  };
+
+  GLSurfaceFormat();
+
+  GLSurfaceFormat(SurfaceFormat format);
+
+  bool IsDefault();
+
+  bool IsSurfaceless();
+
+  bool IsCompatible(GLSurfaceFormat other_format);
+
+  void SetDepthBits(int depth_bits);
+  void SetStencilBits(int stencil_bits);
+  void SetSamples(int samples);
+
+  SurfacePixelLayout GetPixelLayout();
+
+  int GetBufferSize();
+
+ private:
+  bool is_default = true;
+  bool is_surfaceless = false;
+  int red_bits = -1;
+  int green_bits = -1;
+  int blue_bits = -1;
+  int alpha_bits = -1;
+  int depth_bits = -1;
+  int samples = -1;
+  int stencil_bits = -1;
+  SurfacePixelLayout pixel_layout = SURFACE_PIXEL_LAYOUT_DONT_CARE;
+};
+
+}  // namespace gl
+
+#endif  // UI_GL_GL_SURFACE_FORMAT_H_