HUD: Show first paint invalidation in red

HUD: Show first paint invalidation in red

This CL modifies the visualization from cc/heads_up_display,
which is used from the "Show paint rectangles" devtools feature.

Before this CL, all paint invalidations were visualized as green
rectangles. After this CL, paint invalidations from new RenderObjects
are painted in red, and invalidations from existing RenderObjects
 are painted in green.
demo: https://www.youtube.com/watch?v=L-zo91nL2nE

Implementation Overview:
- |WebGraphicsLayerDebugInfo| includes a flag if the current paint
  invalidation is from new RenderObjects. This is to be added in
  https://codereview.chromium.org/474793002/
- An interface |TracedDebugInfo| is introduced to
  to replace raw |ConvertableToTraceFormat| so that the flag can be
  queried from cc code.
- |PictureLayer::Update| queries the flag |includes_new_paint_invalidation()|
  before recording pictures, and pushes the flag to |PictureLayerImpl|.
-- Note: This has to be saved inside PictureLayer, as they are cleared
         after recording.
- |DebugRectHistory::SavePaintRects| saves the paint rects from
  |PictureLayerImpl| which |includes_new_paint_invalidation()| as
  |FIRST_PAINT_RECT_TYPE|.
- |HeadsUpDisplayLayerImpl| paints them in red rects.

BUG=402033

[chrishtr, 2014-08-20 04:28:56]

https://codereview.chromium.org/474783002/diff/40001/cc/layers/layer.cc
File cc/layers/layer.cc (right):

https://codereview.chromium.org/474783002/diff/40001/cc/layers/layer.cc#newco...
cc/layers/layer.cc:874: layer->SetDebugInfo(TakeDebugInfo());
Let's extend the GraphicsLayerDebugInfo struct to include this information as
well, since it is used purely for debugging
purposes. That way there are no new API concepts that are outside of explicit
debugging.

[kouhei (in TOK), 2014-08-25 01:58:13]

PTAL.

[chrishtr, 2014-08-26 18:53:06]

https://codereview.chromium.org/474783002/diff/140001/cc/blink/blink_layer_de...
File cc/blink/blink_layer_debug_info.h (right):

https://codereview.chromium.org/474783002/diff/140001/cc/blink/blink_layer_de...
cc/blink/blink_layer_debug_info.h:20: class BlinkLayerDebugInfo : public
cc::LayerDebugInfo {
Why do you need this interface?

[kouhei (in TOK), 2014-10-01 04:52:55]

I'm going to suspend this for now. I'll focus on visualizing equivalent in
FrameViewer. Also paint invalidation flow will be covered in devtools
invalidation tracking (also wip) too.