content/blimp: Set up hooks for enabling LTHRemote in the renderer.

cc/blimp/layer_tree_host_remote.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/blimp/layer_tree_host_remote.h"
 
 #include "base/atomic_sequence_num.h"
 #include "base/auto_reset.h"
 #include "base/memory/ptr_util.h"
 #include "cc/animation/animation_host.h"
@@ skipping 217 matching lines @@
   return input_handler_weak_ptr_;
 }
 
 void LayerTreeHostRemote::DidStopFlinging() {
   // TODO(khushalsagar): This should not happen. See crbug.com/652000.
   NOTIMPLEMENTED() << "We shouldn't be sending fling gestures to the engine";
 }
 
 void LayerTreeHostRemote::SetDebugState(
     const LayerTreeDebugState& debug_state) {
-  // TODO(khushalsagar): Figure out if we need to send these to the client.
-  NOTREACHED();
+  // If any debugging needs to be enabled, ideally it should be using the
+  // compositor on the client directly. But the setup code will always set this
+  // on initialization, even if the settings end up being a no-op.

[Wez, 2016/10/19 22:15:28]

This comment is rather confusing.  Are you simply saying that LTHR ignores
|debug_state| since there's no actual compositing happening at the sending end -
only the remote end needs to have debug state set?

[Khushal, 2016/10/20 01:29:33]

Yes, only the remoting end should need to have this set and I'm not sure if
there is a use-case for having this plumbed to the client from the engine
through compositor messages, rather than something setting it on the client-side
directly.

I think dev-tools uses this, but I wanted to defer adding it till we know how
that is going to be setup. Wdyt? 

 }
 
 const LayerTreeDebugState& LayerTreeHostRemote::GetDebugState() const {
   return debug_state_;
 }
 
 int LayerTreeHostRemote::ScheduleMicroBenchmark(
     const std::string& benchmark_name,
     std::unique_ptr<base::Value> value,
     const MicroBenchmark::DoneCallback& callback) {
@@ skipping 241 matching lines @@
         layer_tree_host_proto->mutable_layer_updates(), inputs_only);
   layer_tree_->LayersThatShouldPushProperties().clear();
 
   std::vector<PictureData> pictures =
       engine_picture_cache_->CalculateCacheUpdateAndFlush();
   proto::PictureDataVectorToSkPicturesProto(
       pictures, layer_tree_host_proto->mutable_pictures());
 }
 
 }  // namespace cc