cc: More consistent reasoning about display list memory usage.

cc/playback/filter_display_item.cc

Index: cc/playback/filter_display_item.cc
diff --git a/cc/playback/filter_display_item.cc b/cc/playback/filter_display_item.cc
index 5e7771a7d717b474b083be934de6ab0bbade0b45..fbed01509c80ff21641cf5083e9321315af56329 100644
--- a/cc/playback/filter_display_item.cc
+++ b/cc/playback/filter_display_item.cc
@@ -27,10 +27,11 @@ void FilterDisplayItem::SetNew(const FilterOperations& filters,
   filters_ = filters;
   bounds_ = bounds;
 
-  size_t memory_usage =
-      sizeof(skia::RefPtr<SkImageFilter>) + sizeof(gfx::RectF);
+  // FilterOperations doesn't expose its capacity, but size is probably good
+  // enough.
+  size_t external_memory_usage = filters_.size() * sizeof(filters_.at(0));
   DisplayItem::SetNew(true /* suitable_for_gpu_raster */, 1 /* op_count */,
-                      memory_usage);
+                      external_memory_usage);
 }
 
 void FilterDisplayItem::Raster(SkCanvas* canvas,
@@ -62,7 +63,7 @@ void FilterDisplayItem::AsValueInto(
 
 EndFilterDisplayItem::EndFilterDisplayItem() {
   DisplayItem::SetNew(true /* suitable_for_gpu_raster */, 0 /* op_count */,
-                      0 /* memory_usage */);
+                      0 /* external_memory_usage */);
 }
 
 EndFilterDisplayItem::~EndFilterDisplayItem() {