Revert "Re-land deferred compositing updates with fixed assumptions"

Source/core/inspector/InspectorLayerTreeAgent.cpp

Index: Source/core/inspector/InspectorLayerTreeAgent.cpp
diff --git a/Source/core/inspector/InspectorLayerTreeAgent.cpp b/Source/core/inspector/InspectorLayerTreeAgent.cpp
index 5f4df0d79a3582e0b3aacde1c19de3125c906436..2983869aaaf24099e0283a8bad25e912560c7a16 100644
--- a/Source/core/inspector/InspectorLayerTreeAgent.cpp
+++ b/Source/core/inspector/InspectorLayerTreeAgent.cpp
@@ -108,6 +108,8 @@ InspectorLayerTreeAgent::InspectorLayerTreeAgent(InstrumentingAgents* instrument
     , m_frontend(0)
     , m_page(page)
     , m_domAgent(domAgent)
+    , m_notificationTimer(this, &InspectorLayerTreeAgent::notificationTimerFired)
+    , m_notifyAfterNextLayersUpdate(false)
 {
 }
 
@@ -142,10 +144,30 @@ void InspectorLayerTreeAgent::enable(ErrorString*)
 void InspectorLayerTreeAgent::disable(ErrorString*)
 {
     m_instrumentingAgents->setInspectorLayerTreeAgent(0);
+    m_notificationTimer.stop();
 }
 
 void InspectorLayerTreeAgent::layerTreeDidChange()
 {
+    if (m_notificationTimer.isActive())
+        return;
+    if (m_notifyAfterNextLayersUpdate) {
+        m_notifyAfterNextLayersUpdate = false;
+        m_frontend->layerTreeDidChange(buildLayerTree());
+        return;
+    }
+    const double layerTreeUpdateDelayInSeconds = 0.1;
+    m_notificationTimer.startOneShot(layerTreeUpdateDelayInSeconds);
+}
+
+void InspectorLayerTreeAgent::notificationTimerFired(Timer<InspectorLayerTreeAgent>*)
+{
+    RenderLayerCompositor* compositor = renderLayerCompositor();
+    if (compositor && compositor->compositingLayersNeedRebuild()) {
+        // Bad time for building layer tree -- let's do it as soon as it gets rebuild.
+        m_notifyAfterNextLayersUpdate = true;
+        return;
+    }
     m_frontend->layerTreeDidChange(buildLayerTree());
 }
 
@@ -170,6 +192,8 @@ PassRefPtr<TypeBuilder::Array<TypeBuilder::LayerTree::Layer> > InspectorLayerTre
     RenderLayerCompositor* compositor = renderLayerCompositor();
     if (!compositor || !compositor->inCompositingMode())
         return 0;
+    // Caller is responsible for only calling this when layer tree is up to date (preferrably just in the end of RenderLayerCompositor::updateCompositingLayers()
+    ASSERT(!compositor->compositingLayersNeedRebuild());
     LayerIdToNodeIdMap layerIdToNodeIdMap;
     RefPtr<TypeBuilder::Array<TypeBuilder::LayerTree::Layer> > layers = TypeBuilder::Array<TypeBuilder::LayerTree::Layer>::create();
     buildLayerIdToNodeIdMap(compositor->rootRenderLayer(), layerIdToNodeIdMap);