Add a Display and ContextProvider concept to mojom, use to recreate

examples/sample_app/spinning_cube.cc

 // Copyright 2013 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.
 
 // This example program is based on Simple_VertexShader.c from:
 
 //
 // Book:      OpenGL(R) ES 2.0 Programming Guide
 // Authors:   Aaftab Munshi, Dan Ginsburg, Dave Shreiner
 // ISBN-10:   0321502795
@@ skipping 421 matching lines @@
   if (!initialized_)
     return;
   if (state_->vbo_vertices_)
     glDeleteBuffers(1, &state_->vbo_vertices_);
   if (state_->vbo_indices_)
     glDeleteBuffers(1, &state_->vbo_indices_);
   if (state_->program_object_)
     glDeleteProgram(state_->program_object_);
 }
 
-void SpinningCube::Init(uint32_t width, uint32_t height) {
-  width_ = width;
-  height_ = height;
-
+void SpinningCube::Init() {
   const char vertex_shader_source[] =
       "uniform mat4 u_mvpMatrix;                                       \n"
       "attribute vec4 a_position;                                      \n"
       "attribute vec4 a_normal;                                        \n"
       "varying vec4 v_color;                                           \n"
       "void main()                                                     \n"
       "{                                                               \n"
       "   gl_Position = u_mvpMatrix * a_position;                      \n"
       "   vec4 rotated_normal = u_mvpMatrix * a_normal;                \n"
       "   vec4 light_direction = normalize(vec4(0.0, 1.0, -1.0, 0.0)); \n"
@@ skipping 23 matching lines @@
   state_->num_indices_ = GenerateCube(
       &state_->vbo_vertices_, &state_->vbo_indices_);
 
   glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
   glEnable(GL_DEPTH_TEST);
   initialized_ = true;
 }
 
 void SpinningCube::OnGLContextLost() {
   initialized_ = false;
-  height_ = 0;
-  width_ = 0;
   state_->OnGLContextLost();
 }
 
 void SpinningCube::SetFlingMultiplier(float drag_distance,
                                       float drag_time) {
   fling_multiplier_ = RotationForDragDistance(drag_distance) /
       RotationForTimeDelta(drag_time);
 
 }
 
@@ skipping 47 matching lines @@
 
   ESMatrix modelview;
   modelview.LoadIdentity();
   modelview.Translate(0.0, 0.0, -2.0);
   modelview.Rotate(state_->angle_ * direction_, 1.0, 0.0, 1.0);
 
   state_->mvp_matrix_.Multiply(&modelview, &perspective);
 }
 
 }  // namespace examples