Add basic GL functionality to the passthrough command buffer.

gpu/command_buffer/service/texture_manager.h

Index: gpu/command_buffer/service/texture_manager.h
diff --git a/gpu/command_buffer/service/texture_manager.h b/gpu/command_buffer/service/texture_manager.h
index 1614c72a225d0fe0acff42a0d77e9f4f38ae8117..ddbe192e910edca5fe1ff1a56da6cdec45e9d0c6 100644
--- a/gpu/command_buffer/service/texture_manager.h
+++ b/gpu/command_buffer/service/texture_manager.h
@@ -65,6 +65,22 @@ class GPU_EXPORT TextureBase {
   MailboxManager* mailbox_manager_;
 };
 
+// A ref-counted version of the TextureBase class that deletes the texture after
+// all references have been released.
+class TexturePassthrough final : public TextureBase,
+                                 public base::RefCounted<TexturePassthrough> {
+ public:
+  explicit TexturePassthrough(GLuint service_id);
+
+ protected:
+  ~TexturePassthrough() override;
+
+ private:
+  friend class base::RefCounted<TexturePassthrough>;
+
+  DISALLOW_COPY_AND_ASSIGN(TexturePassthrough);
+};
+
 // Info about Textures currently in the system.
 // This class wraps a real GL texture, keeping track of its meta-data. It is
 // jointly owned by possibly multiple TextureRef.