Add LayerTreeHostClient::{will,did}UpdateLayer, report layer updates to DevTools

cc/trees/layer_tree_host.cc

Index: cc/trees/layer_tree_host.cc
diff --git a/cc/trees/layer_tree_host.cc b/cc/trees/layer_tree_host.cc
index 25366468f7d94cb79e7684661397e9aff288301f..45ed62ec8402035b92fa1fda0bd6463d592a73a5 100644
--- a/cc/trees/layer_tree_host.cc
+++ b/cc/trees/layer_tree_host.cc
@@ -17,6 +17,7 @@
 #include "cc/animation/animation_registrar.h"
 #include "cc/animation/layer_animation_controller.h"
 #include "cc/base/math_util.h"
+#include "cc/debug/devtools_instrumentation.h"
 #include "cc/debug/overdraw_metrics.h"
 #include "cc/debug/rendering_stats_instrumentation.h"
 #include "cc/input/top_controls_manager.h"
@@ -72,6 +73,8 @@ scoped_ptr<LayerTreeHost> LayerTreeHost::Create(
   return layer_tree_host.Pass();
 }
 
+static int s_next_tree_id = 1;
+
 LayerTreeHost::LayerTreeHost(LayerTreeHostClient* client,
                              const LayerTreeSettings& settings)
     : animating_(false),
@@ -100,7 +103,9 @@ LayerTreeHost::LayerTreeHost(LayerTreeHostClient* client,
   if (settings_.accelerated_animation_enabled)
     animation_registrar_ = AnimationRegistrar::Create();
   s_num_layer_tree_instances++;
-
+  if (s_next_tree_id <= 0)
+      s_next_tree_id = 1;
+  tree_id_ = s_next_tree_id++;
   rendering_stats_instrumentation_->set_record_rendering_stats(
       debug_state_.RecordRenderingStats());
 }
@@ -946,6 +951,8 @@ bool LayerTreeHost::PaintLayerContents(
              it->render_surface()->draw_opacity_is_animating());
       need_more_updates |= PaintMasksForRenderSurface(*it, queue, stats_ptr);

[nduca, 2013/06/26 15:08:01]

hmm, should we do a followup bug for figuring out this half of the branch....

     } else if (it.represents_itself()) {
+      devtools_instrumentation::ScopedLayerTreeTask
+          update_layer(devtools_instrumentation::kUpdateLayer, it->id(), id());
       DCHECK(!it->paint_properties().bounds.IsEmpty());
       it->Update(queue, &occlusion_tracker, stats_ptr);
       need_more_updates |= it->NeedMoreUpdates();