cc: Add frame timing request plumbing through the layers.

cc/layers/layer.cc

Index: cc/layers/layer.cc
diff --git a/cc/layers/layer.cc b/cc/layers/layer.cc
index 3817115f709780042a40cecba6ec00312185b0b2..b45998e1b375dac52d6ae39e3352e86a141497b5 100644
--- a/cc/layers/layer.cc
+++ b/cc/layers/layer.cc
@@ -79,7 +79,8 @@ Layer::Layer()
       clip_parent_(nullptr),
       replica_layer_(nullptr),
       raster_scale_(0.f),
-      client_(nullptr) {
+      client_(nullptr),
+      frame_timing_requests_dirty_(false) {
   layer_animation_controller_ = LayerAnimationController::Create(layer_id_);
   layer_animation_controller_->AddValueObserver(this);
   layer_animation_controller_->set_value_provider(this);
@@ -1016,6 +1017,11 @@ void Layer::PushPropertiesTo(LayerImpl* layer) {
   layer_animation_controller_->PushAnimationUpdatesTo(
       layer->layer_animation_controller());
 
+  if (frame_timing_requests_dirty_) {

[danakj, 2015/01/23 18:08:45]

what's the reason for these dirty flags?

in case we commit twice in a row before consuming the requests on the other end?
we could do that if dirty was true twice too.

[vmpstr, 2015/01/23 18:41:57]

It's just so we don't keep copying the same vector. Once we set some requests,
those requests are in effect until something else is set, so this avoids
propagating the same thing on each commit/activation.

[danakj, 2015/01/23 18:43:29]

I see, you need them to stick around for multiple frames? Do you need them to
stick around on all of the layers? Could you just swap() them thru to the active
layer?

[vmpstr, 2015/01/23 18:45:58]

They really only need to be on the active layer.. Swapping would only work with
the dirty flag, since otherwise we'd swap back the next time, but other than
that it could work. Any suggestions for a function name? Liek
layer->TakeFrameTimingRequests(&frame_timing_requests_) or something?

+    layer->SetFrameTimingRequests(frame_timing_requests_);
+    frame_timing_requests_dirty_ = false;
+  }
+
   // Reset any state that should be cleared for the next update.
   stacking_order_changed_ = false;
   update_rect_ = gfx::Rect();
@@ -1294,4 +1300,11 @@ gfx::Transform Layer::draw_transform_from_property_trees(
   return xform;
 }
 
+void Layer::SetFrameTimingRequests(
+    const std::vector<FrameTimingRequest>& requests) {
+  frame_timing_requests_ = requests;
+  frame_timing_requests_dirty_ = true;
+  SetNeedsCommit();
+}
+
 }  // namespace cc