gpu: Use a VAO as required by the core profile in ClearFramebuffer

gpu/command_buffer/service/gles2_cmd_clear_framebuffer.cc

 // Copyright 2014 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.
 
 #include "gpu/command_buffer/service/gles2_cmd_clear_framebuffer.h"
 
 #include "gpu/command_buffer/service/gl_utils.h"
 #include "gpu/command_buffer/service/gles2_cmd_decoder.h"
 #include "ui/gfx/geometry/size.h"
 
@@ skipping 38 matching lines @@
     DLOG(ERROR) << "Shader compilation failure.";
   }
 #endif
 }
 
 }  // namespace
 
 namespace gpu {
 
 ClearFramebufferResourceManager::ClearFramebufferResourceManager(
-    const gles2::GLES2Decoder* decoder)
-    : initialized_(false), program_(0u), buffer_id_(0u) {
-  Initialize(decoder);
+    const gles2::GLES2Decoder* decoder,
+    const gles2::FeatureInfo::FeatureFlags& feature_flags)
+    : initialized_(false), program_(0u), vao_(0), buffer_id_(0u) {
+  Initialize(decoder, feature_flags);
 }
 
 ClearFramebufferResourceManager::~ClearFramebufferResourceManager() {
   Destroy();
   DCHECK(!buffer_id_);
 }
 
 void ClearFramebufferResourceManager::Initialize(
-    const gles2::GLES2Decoder* decoder) {
+    const gles2::GLES2Decoder* decoder,
+    const gles2::FeatureInfo::FeatureFlags& feature_flags) {
   static_assert(
       kVertexPositionAttrib == 0u,
       "kVertexPositionAttrib must be 0");
+
   DCHECK(!buffer_id_);
-
   glGenBuffersARB(1, &buffer_id_);
   glBindBuffer(GL_ARRAY_BUFFER, buffer_id_);
   const GLfloat kQuadVertices[] = {-1.0f, -1.0f,
                                     1.0f, -1.0f,
                                     1.0f,  1.0f,
                                    -1.0f,  1.0f};
   glBufferData(
       GL_ARRAY_BUFFER, sizeof(kQuadVertices), kQuadVertices, GL_STATIC_DRAW);
+
+  DCHECK(!vao_);
+
+  if (feature_flags.native_vertex_array_object) {
+    glGenVertexArraysOES(1, &vao_);
+
+    glBindVertexArrayOES(vao_);
+    glEnableVertexAttribArray(kVertexPositionAttrib);
+    glVertexAttribPointer(kVertexPositionAttrib, 2, GL_FLOAT, GL_FALSE, 0, 0);
+
+    decoder->RestoreAllAttributes();
+  }
+
   decoder->RestoreBufferBindings();
   initialized_ = true;
 }
 
 void ClearFramebufferResourceManager::Destroy() {
   if (!initialized_)
     return;
 
   glDeleteProgram(program_);
+
+  if (vao_ != 0) {
+    glDeleteVertexArraysOES(1, &vao_);
+    vao_ = 0;
+  }
+
   glDeleteBuffersARB(1, &buffer_id_);
   buffer_id_ = 0;
 }
 
 void ClearFramebufferResourceManager::ClearFramebuffer(
     const gles2::GLES2Decoder* decoder,
     const gfx::Size& framebuffer_size,
     GLbitfield mask,
     GLfloat clear_color_red,
     GLfloat clear_color_green,
@@ skipping 30 matching lines @@
   glUseProgram(program_);
 
 #if DCHECK_IS_ON()
   glValidateProgram(program_);
   GLint validation_status = GL_FALSE;
   glGetProgramiv(program_, GL_VALIDATE_STATUS, &validation_status);
   if (GL_TRUE != validation_status)
     DLOG(ERROR) << "Invalid shader.";
 #endif
 
-  decoder->ClearAllAttributes();
-  glEnableVertexAttribArray(kVertexPositionAttrib);
-
-  glBindBuffer(GL_ARRAY_BUFFER, buffer_id_);
-  glVertexAttribPointer(kVertexPositionAttrib, 2, GL_FLOAT, GL_FALSE, 0, 0);
+  if (vao_) {
+    glBindVertexArrayOES(vao_);
+  } else {
+    decoder->ClearAllAttributes();
+    glBindBuffer(GL_ARRAY_BUFFER, buffer_id_);
+    glEnableVertexAttribArray(kVertexPositionAttrib);
+    glVertexAttribPointer(kVertexPositionAttrib, 2, GL_FLOAT, GL_FALSE, 0, 0);
+  }
 
   glUniform1f(depth_handle_, clear_depth_value);
   glUniform4f(color_handle_, clear_color_red, clear_color_green,
               clear_color_blue, clear_color_alpha);
 
   if (!(mask & GL_COLOR_BUFFER_BIT)) {
     glColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE);
   }
 
   if (mask & GL_DEPTH_BUFFER_BIT) {
@@ skipping 14 matching lines @@
     glStencilMask(0);
   }
 
   glDisable(GL_CULL_FACE);
   glDisable(GL_BLEND);
   glDisable(GL_POLYGON_OFFSET_FILL);
 
   glViewport(0, 0, framebuffer_size.width(), framebuffer_size.height());
   glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
 
+  if (vao_ == 0) {
+    decoder->RestoreBufferBindings();
+  }
   decoder->RestoreAllAttributes();
   decoder->RestoreProgramBindings();
-  decoder->RestoreBufferBindings();
   decoder->RestoreGlobalState();
 }
 
 }  // namespace gpu