command_buffer: Implement EXT_blend_func_extended

gpu/command_buffer/service/context_group.cc

Index: gpu/command_buffer/service/context_group.cc
diff --git a/gpu/command_buffer/service/context_group.cc b/gpu/command_buffer/service/context_group.cc
index 7e5589f48ef5e658d00276903b8e03a4cae21ee7..cb1e185bca2fe6ecb31cbfd2e59a077d5cebf6be 100644
--- a/gpu/command_buffer/service/context_group.cc
+++ b/gpu/command_buffer/service/context_group.cc
@@ -68,6 +68,7 @@ ContextGroup::ContextGroup(
       max_vertex_uniform_vectors_(0u),
       max_color_attachments_(1u),
       max_draw_buffers_(1u),
+      max_dual_source_draw_buffers_(0u),
       program_cache_(NULL),
       feature_info_(feature_info) {
   {
@@ -143,6 +144,11 @@ bool ContextGroup::Initialize(GLES2Decoder* decoder,
     if (max_draw_buffers_ < 1)
       max_draw_buffers_ = 1;
   }
+  if (feature_info_->feature_flags().ext_blend_func_extended) {
+    GetIntegerv(GL_MAX_DUAL_SOURCE_DRAW_BUFFERS_EXT,
+                &max_dual_source_draw_buffers_);
+    DCHECK(max_dual_source_draw_buffers_ >= 1);
+  }
 
   buffer_manager_.reset(
       new BufferManager(memory_tracker_.get(), feature_info_.get()));
@@ -289,8 +295,9 @@ bool ContextGroup::Initialize(GLES2Decoder* decoder,
 
   path_manager_.reset(new PathManager());
 
-  program_manager_.reset(new ProgramManager(
-      program_cache_, max_varying_vectors_, feature_info_.get()));
+  program_manager_.reset(
+      new ProgramManager(program_cache_, max_varying_vectors_,
+                         max_dual_source_draw_buffers_, feature_info_.get()));
 
   if (!texture_manager_->Initialize()) {
     LOG(ERROR) << "Context::Group::Initialize failed because texture manager "