Add initial GLImage tracing + stubs

ui/gl/gl_image_shared_memory.h

Index: ui/gl/gl_image_shared_memory.h
diff --git a/ui/gl/gl_image_shared_memory.h b/ui/gl/gl_image_shared_memory.h
index 231675b714185638ac4b4bbb203db6244a37f631..ce9e30838b6671f818307d744df9061a116a2ef6 100644
--- a/ui/gl/gl_image_shared_memory.h
+++ b/ui/gl/gl_image_shared_memory.h
@@ -21,10 +21,15 @@ class GL_EXPORT GLImageSharedMemory : public GLImageMemory {
   // Overridden from GLImage:
   void Destroy(bool have_context) override;
 
+  void DumpMemory(base::trace_event::ProcessMemoryDump* pmd,
+                  uint64_t process_tracing_id,
+                  const std::string& dump_name) override;
+
  protected:
   ~GLImageSharedMemory() override;
 
  private:
+  base::trace_event::GenericSharedMemoryId shared_memory_id_;
   scoped_ptr<base::SharedMemory> shared_memory_;
 
   DISALLOW_COPY_AND_ASSIGN(GLImageSharedMemory);