Implement EXT_draw_buffers WebGL extention support in command buffer.

gpu/command_buffer/service/context_group.cc

 // Copyright (c) 2012 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/context_group.h"
 
 #include <algorithm>
 #include <string>
 
 #include "base/command_line.h"
@@ skipping 28 matching lines @@
       enforce_gl_minimums_(CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kEnforceGLMinimums)),
       bind_generates_resource_(bind_generates_resource),
       max_vertex_attribs_(0u),
       max_texture_units_(0u),
       max_texture_image_units_(0u),
       max_vertex_texture_image_units_(0u),
       max_fragment_uniform_vectors_(0u),
       max_varying_vectors_(0u),
       max_vertex_uniform_vectors_(0u),
+      max_color_attachments_(1u),
+      max_draw_buffers_(1u),
       program_cache_(NULL),
       feature_info_(new FeatureInfo()) {
   {
     TransferBufferManager* manager = new TransferBufferManager();
     transfer_buffer_manager_.reset(manager);
     manager->Initialize();
   }
 
   id_namespaces_[id_namespaces::kBuffers].reset(new IdAllocator);
   id_namespaces_[id_namespaces::kFramebuffers].reset(new IdAllocator);
@@ skipping 119 matching lines @@
   } else {
     GetIntegerv(
         GL_MAX_FRAGMENT_UNIFORM_COMPONENTS, &max_fragment_uniform_vectors_);
     max_fragment_uniform_vectors_ /= 4;
     GetIntegerv(GL_MAX_VARYING_FLOATS, &max_varying_vectors_);
     max_varying_vectors_ /= 4;
     GetIntegerv(GL_MAX_VERTEX_UNIFORM_COMPONENTS, &max_vertex_uniform_vectors_);
     max_vertex_uniform_vectors_ /= 4;
   }
 
+  if (feature_info_->feature_flags().ext_draw_buffers) {
+    GetIntegerv(GL_MAX_COLOR_ATTACHMENTS_EXT, &max_color_attachments_);
+    GetIntegerv(GL_MAX_DRAW_BUFFERS_ARB, &max_draw_buffers_);
+  }
+
   const GLint kMinFragmentUniformVectors = 16;
   const GLint kMinVaryingVectors = 8;
   const GLint kMinVertexUniformVectors = 128;
   if (!CheckGLFeatureU(
       kMinFragmentUniformVectors, &max_fragment_uniform_vectors_) ||
       !CheckGLFeatureU(kMinVaryingVectors, &max_varying_vectors_) ||
       !CheckGLFeatureU(
       kMinVertexUniformVectors, &max_vertex_uniform_vectors_)) {
     LOG(ERROR) << "ContextGroup::Initialize failed because too few "
                << "uniforms or varyings supported.";
@@ skipping 127 matching lines @@
     GLenum pname, GLint min_required, uint32* v) {
   uint32 value = 0;
   GetIntegerv(pname, &value);
   bool result = CheckGLFeatureU(min_required, &value);
   *v = value;
   return result;
 }
 
 }  // namespace gles2
 }  // namespace gpu