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 4865fe2bd2c4376e93b9248ac1f6e0bdb37a0780..6f60f3cfa8ad79ac0730c9515d4ba526567897d5 100644
--- a/cc/layers/layer_impl.cc
+++ b/cc/layers/layer_impl.cc
@@ -254,10 +254,19 @@ void LayerImpl::SetSentScrollDelta(gfx::Vector2d sent_scroll_delta) {
   if (sent_scroll_delta_ == sent_scroll_delta)
     return;
 
+  TRACE_EVENT2("impl-scroll",
+               "LayerImpl::SetSentScrollDelta",
+               "scrollX", sent_scroll_delta.x(),

[danakj, 2013/07/29 17:16:08]

scroll_x?

+               "scrollY", sent_scroll_delta.y());

[danakj, 2013/07/29 17:16:08]

scroll_y?

+
   sent_scroll_delta_ = sent_scroll_delta;
 }
 
 gfx::Vector2dF LayerImpl::ScrollBy(gfx::Vector2dF scroll) {
+  TRACE_EVENT2("impl-scroll",
+               "LayerImpl::ScrollBy",
+               "scrollX", scroll.x(),

[danakj, 2013/07/29 17:16:08]

same.

consider making a base::Value containing the data and passing that to the event,
instead of passing values directly, so we can add more things in the future more
easily.

[enne (OOO), 2013/07/29 17:46:31]

Even better, add a MathUtil::AsValue for gfx::Vector2d.

+               "scrollY", scroll.y());
   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.
@@ -274,12 +283,16 @@ 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",

[danakj, 2013/07/29 17:16:08]

Should we drop these from the "cc" category then?

+        "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",

[danakj, 2013/07/29 17:16:08]

i think "impl" as a name is something to avoid and not as
discoverable/understandable to people in general. what about just calling these
"scroll[ing?]"? wdyt?

[enne (OOO), 2013/07/29 17:46:31]

Do you think there'll ever be a blink scrolling trace? What about cc-scroll?

+        "LayerImpl::TryScroll: Ignored NonInvertibleTransform",
+        TRACE_EVENT_SCOPE_THREAD);
     return InputHandler::ScrollIgnored;
   }
 
@@ -304,29 +317,40 @@ 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,
+      "layerId", id());

[danakj, 2013/07/29 17:16:08]

layer_id?

+
   return InputHandler::ScrollStarted;
 }
 
@@ -874,6 +898,11 @@ void LayerImpl::SetScrollDelta(gfx::Vector2dF scroll_delta) {
   if (ScrollDelta() == scroll_delta)
     return;
 
+  TRACE_EVENT2("impl-scroll",
+               "LayerImpl::SetScrollDelta",
+               "scroll_delta.x", scroll_delta.x(),
+               "scroll_delta.y", scroll_delta.y());
+
   if (layer_tree_impl()->IsActiveTree()) {
     LayerImpl* pending_twin = layer_tree_impl()->FindPendingTreeLayerById(id());
     if (pending_twin) {
@@ -1106,6 +1135,9 @@ void LayerImpl::AsValueInto(base::DictionaryValue* state) const {
       &clipped);
   state->Set("layer_quad", MathUtil::AsValue(layer_quad).release());
 
+#ifndef NDEBUG

[danakj, 2013/07/29 17:16:08]

Why only in not NDEBUG?

[enne (OOO), 2013/07/29 17:46:31]

Layers only get their names set in debug builds.  You're welcome to land this,
but there's some work in progress being done to pull names from Blink but only
when tracing is on, rather than always pushing names from Blink only for debug
builds.

See: https://codereview.chromium.org/18473002/ or
https://codereview.chromium.org/16903005/.

+  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)