Add impl/comp scrolling instrumentation.

cc/layers/layer_impl.cc

Index: cc/layers/layer_impl.cc
diff --git a/cc/layers/layer_impl.cc b/cc/layers/layer_impl.cc
index 480cee0db3683360c8419e65cc2c564d09ca2c90..3856ba5af16b662f50b79087cfea36a31f029156 100644
--- a/cc/layers/layer_impl.cc
+++ b/cc/layers/layer_impl.cc
@@ -255,12 +255,24 @@ void LayerImpl::SetSentScrollDelta(gfx::Vector2d sent_scroll_delta) {
   if (sent_scroll_delta_ == sent_scroll_delta)
     return;
 
+  scoped_ptr<base::Value> value = MathUtil::AsValue(sent_scroll_delta);
+  TRACE_EVENT1("impl-scroll",
+               "LayerImpl::SetSentScrollDelta",
+               "sent_scroll_delta",
+               TracedValue::FromValue(value.release()));
+
   sent_scroll_delta_ = sent_scroll_delta;
 }
 
 gfx::Vector2dF LayerImpl::ScrollBy(gfx::Vector2dF scroll) {
   DCHECK(scrollable());
 
+  scoped_ptr<base::Value> value = MathUtil::AsValue(scroll);
+  TRACE_EVENT1("impl-scroll",
+               "LayerImpl::ScrollBy",
+               "scroll",
+               TracedValue::FromValue(value.release()));
+
   gfx::Vector2dF min_delta = -scroll_offset_;
   gfx::Vector2dF max_delta = max_scroll_offset_ - scroll_offset_;
   // Clamp new_delta so that position + delta stays within scroll bounds.
@@ -295,13 +307,18 @@ void LayerImpl::ApplySentScrollDeltas() {
 InputHandler::ScrollStatus LayerImpl::TryScroll(
     gfx::PointF screen_space_point,
     InputHandler::ScrollInputType type) const {
+
   if (should_scroll_on_main_thread()) {
-    TRACE_EVENT0("cc", "LayerImpl::TryScroll: Failed ShouldScrollOnMainThread");
+    TRACE_EVENT_INSTANT0("cc,impl-scroll",
+        "LayerImpl::TryScroll: Failed ShouldScrollOnMainThread",
+        TRACE_EVENT_SCOPE_THREAD);
     return InputHandler::ScrollOnMainThread;
   }
 
   if (!screen_space_transform().IsInvertible()) {
-    TRACE_EVENT0("cc", "LayerImpl::TryScroll: Ignored NonInvertibleTransform");
+    TRACE_EVENT_INSTANT0("cc,impl-scroll",
+        "LayerImpl::TryScroll: Ignored NonInvertibleTransform",
+        TRACE_EVENT_SCOPE_THREAD);
     return InputHandler::ScrollIgnored;
   }
 
@@ -326,29 +343,40 @@ InputHandler::ScrollStatus LayerImpl::TryScroll(
     if (!clipped &&
         non_fast_scrollable_region().Contains(
             gfx::ToRoundedPoint(hit_test_point_in_layer_space))) {
-      TRACE_EVENT0("cc",
-                   "LayerImpl::tryScroll: Failed NonFastScrollableRegion");
+      TRACE_EVENT_INSTANT0("cc,impl-scroll",
+        "LayerImpl::TryScroll: Failed NonFastScrollableRegion",
+        TRACE_EVENT_SCOPE_THREAD);
       return InputHandler::ScrollOnMainThread;
     }
   }
 
   if (type == InputHandler::Wheel && have_wheel_event_handlers()) {
-    TRACE_EVENT0("cc", "LayerImpl::tryScroll: Failed WheelEventHandlers");
+    TRACE_EVENT_INSTANT0("cc,impl-scroll",
+        "LayerImpl::TryScroll: Failed WheelEventHandlers",
+        TRACE_EVENT_SCOPE_THREAD);
     return InputHandler::ScrollOnMainThread;
   }
 
   if (!scrollable()) {
-    TRACE_EVENT0("cc", "LayerImpl::tryScroll: Ignored not scrollable");
+    TRACE_EVENT_INSTANT0("cc,impl-scroll",
+        "LayerImpl::TryScroll: Ignored not scrollable",
+        TRACE_EVENT_SCOPE_THREAD);
     return InputHandler::ScrollIgnored;
   }
 
   if (max_scroll_offset_.x() <= 0 && max_scroll_offset_.y() <= 0) {
-    TRACE_EVENT0("cc",
-                 "LayerImpl::tryScroll: Ignored. Technically scrollable,"
-                 " but has no affordance in either direction.");
+    TRACE_EVENT_INSTANT0("cc,impl-scroll",
+        "LayerImpl::TryScroll: Ignored. Technically scrollable,"
+        " but has no affordance in either direction.",
+        TRACE_EVENT_SCOPE_THREAD);
     return InputHandler::ScrollIgnored;
   }
 
+  TRACE_EVENT_INSTANT1("cc,impl-scroll",
+      "LayerImpl::TryScroll: Started",
+      TRACE_EVENT_SCOPE_THREAD,
+      "layer_id", id());
+
   return InputHandler::ScrollStarted;
 }
 
@@ -896,6 +924,12 @@ void LayerImpl::SetScrollDelta(gfx::Vector2dF scroll_delta) {
   if (ScrollDelta() == scroll_delta)
     return;
 
+  scoped_ptr<base::Value> value = MathUtil::AsValue(scroll_delta);
+  TRACE_EVENT1("impl-scroll",
+               "LayerImpl::SetScrollDelta",
+               "delta",
+               TracedValue::FromValue(value.release()));
+
   if (layer_tree_impl()->IsActiveTree()) {
     LayerImpl* pending_twin = layer_tree_impl()->FindPendingTreeLayerById(id());
     if (pending_twin) {
@@ -1128,6 +1162,9 @@ void LayerImpl::AsValueInto(base::DictionaryValue* state) const {
       &clipped);
   state->Set("layer_quad", MathUtil::AsValue(layer_quad).release());
 
+#ifndef NDEBUG
+  state->SetString("debug_name", debug_name_);
+#endif
 
   scoped_ptr<base::ListValue> children_list(new base::ListValue());
   for (size_t i = 0; i < children_.size(); ++i)