Add basic GL functionality to the passthrough command buffer.

gpu/command_buffer/service/texture_manager.cc

Index: gpu/command_buffer/service/texture_manager.cc
diff --git a/gpu/command_buffer/service/texture_manager.cc b/gpu/command_buffer/service/texture_manager.cc
index 8899aaee3edf69bcbeb6604863f993b21afe53bc..dfcf921e50083ae380e8a9ea0c4bb013d80ef22f 100644
--- a/gpu/command_buffer/service/texture_manager.cc
+++ b/gpu/command_buffer/service/texture_manager.cc
@@ -372,6 +372,14 @@ void TextureBase::SetMailboxManager(MailboxManager* mailbox_manager) {
   mailbox_manager_ = mailbox_manager;
 }
 
+TexturePassthrough::TexturePassthrough(GLuint service_id)
+    : TextureBase(service_id) {}
+
+TexturePassthrough::~TexturePassthrough() {
+  DeleteFromMailboxManager();
+  glDeleteTextures(1, &service_id_);
+}
+
 Texture::Texture(GLuint service_id)
     : TextureBase(service_id),
       memory_tracking_ref_(NULL),