cc: Ensure that large damage doesn't register as "frame has no damage"

cc/debug/debug_rect_history.cc

Index: cc/debug/debug_rect_history.cc
diff --git a/cc/debug/debug_rect_history.cc b/cc/debug/debug_rect_history.cc
index de8bfc2cc2f84f5922837b9d3fc31ff0d98dceb5..8472c28f7f95c84a400299fccb67897804a61424 100644
--- a/cc/debug/debug_rect_history.cc
+++ b/cc/debug/debug_rect_history.cc
@@ -125,11 +125,15 @@ void DebugRectHistory::SaveSurfaceDamageRects(
     RenderSurfaceImpl* render_surface = render_surface_layer->render_surface();
     DCHECK(render_surface);
 
-    debug_rects_.push_back(DebugRect(
-        SURFACE_DAMAGE_RECT_TYPE,
-        MathUtil::MapEnclosingClippedRect(
-            render_surface->screen_space_transform(),
-            render_surface->damage_tracker()->current_damage_rect())));
+    gfx::Rect damage_rect;
+    bool is_valid_rect =
+        render_surface->damage_tracker()->GetDamageRectIfValid(&damage_rect);

[enne (OOO), 2017/01/19 23:23:39]

Maybe encapsulate this conditional block in a RenderSurfaceImpl::GetDamageRect()
function since you do it three times?

[danakj, 2017/01/20 17:03:04]

My one thot on this is that then you have 2 ways to get a damage rect, one on
RSI and one on it's DamageTracker. It might be nice to not allow access to the
DamageTracker directly, but there's like 3 or 4 other methods we use from
LayerTreeHostImpl so idk..

[vmpstr, 2017/01/20 21:38:18]

I think it still makes sense, since the two accessors have slightly different
results: The RS one always returns a rect (if the damage was invalid, it just
returns the content rect). However, the damage tracker one provides more fine
grained information: either a rect, or information that the rect wasn't valid.

I agree that hiding damage tracker might be nice, but then that means adding
some forwarding functions to the render surface, which I'd like to avoid in this
patch.

[vmpstr, 2017/01/20 21:38:18]

Done.

+    if (!is_valid_rect)
+      damage_rect = render_surface->content_rect();
+    debug_rects_.push_back(
+        DebugRect(SURFACE_DAMAGE_RECT_TYPE,
+                  MathUtil::MapEnclosingClippedRect(
+                      render_surface->screen_space_transform(), damage_rect)));
   }
 }