Add basic GL functionality to the passthrough command buffer.

gpu/command_buffer/service/gles2_cmd_decoder_passthrough.cc

Index: gpu/command_buffer/service/gles2_cmd_decoder_passthrough.cc
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder_passthrough.cc b/gpu/command_buffer/service/gles2_cmd_decoder_passthrough.cc
index f3a19dc7527d93446ccadc38cbbb9e8ac4fbca2c..d921ac3542c0c171358f961370a413f00cd49834 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder_passthrough.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder_passthrough.cc
@@ -11,6 +11,10 @@
 namespace gpu {
 namespace gles2 {
 
+PassthroughResources::PassthroughResources() {}
+
+PassthroughResources::~PassthroughResources() {}
+
 GLES2DecoderPassthroughImpl::GLES2DecoderPassthroughImpl(ContextGroup* group)
     : commands_to_process_(0),
       debug_marker_manager_(),
@@ -113,6 +117,17 @@ bool GLES2DecoderPassthroughImpl::Initialize(
 
   image_manager_.reset(new ImageManager());
 
+  resources_ = group_->passthrough_resources();
+
+  mailbox_manager_ = group_->mailbox_manager();
+
+  // Query information about the texture units
+  GLint num_texture_units = 0;
+  glGetIntegerv(GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS, &num_texture_units);
+
+  active_texture_unit_ = 0;
+  bound_textures_.resize(num_texture_units, 0);
+
   set_initialized();
   return true;
 }
@@ -175,11 +190,11 @@ gl::GLContext* GLES2DecoderPassthroughImpl::GetGLContext() {
 }
 
 gpu::gles2::ContextGroup* GLES2DecoderPassthroughImpl::GetContextGroup() {
-  return nullptr;
+  return group_.get();
 }
 
 const FeatureInfo* GLES2DecoderPassthroughImpl::GetFeatureInfo() const {
-  return nullptr;
+  return group_->feature_info();
 }
 
 gpu::Capabilities GLES2DecoderPassthroughImpl::GetCapabilities() {
@@ -294,10 +309,14 @@ size_t GLES2DecoderPassthroughImpl::GetCreatedBackTextureCountForTest() {
 }
 
 void GLES2DecoderPassthroughImpl::SetFenceSyncReleaseCallback(
-    const FenceSyncReleaseCallback& callback) {}
+    const FenceSyncReleaseCallback& callback) {
+  fence_sync_release_callback_ = callback;
+}
 
 void GLES2DecoderPassthroughImpl::SetWaitFenceSyncCallback(
-    const WaitFenceSyncCallback& callback) {}
+    const WaitFenceSyncCallback& callback) {
+  wait_fence_sync_callback_ = callback;
+}
 
 void GLES2DecoderPassthroughImpl::SetDescheduleUntilFinishedCallback(
     const NoParamCallback& callback) {}
@@ -344,7 +363,8 @@ void GLES2DecoderPassthroughImpl::PerformPollingWork() {}
 bool GLES2DecoderPassthroughImpl::GetServiceTextureId(
     uint32_t client_texture_id,
     uint32_t* service_texture_id) {
-  return false;
+  return resources_->texture_id_map.GetServiceID(client_texture_id,
+                                                 service_texture_id);
 }
 
 gpu::error::ContextLostReason