Revert of cc: Replace recorded region with direct map lookup

cc/layers/picture_layer_impl.cc

Index: cc/layers/picture_layer_impl.cc
diff --git a/cc/layers/picture_layer_impl.cc b/cc/layers/picture_layer_impl.cc
index 2faa67bfe594b56e297f680b492824f053c026f5..e9c2c8e31b10c054201edb6cdb62b220d44d5773 100644
--- a/cc/layers/picture_layer_impl.cc
+++ b/cc/layers/picture_layer_impl.cc
@@ -855,7 +855,8 @@
 
   PictureLayerTiling* tiling = tilings_->AddTiling(contents_scale);
 
-  DCHECK(pile_->HasRecordings());
+  const Region& recorded = pile_->recorded_region();
+  DCHECK(!recorded.IsEmpty());
 
   if (twin_layer_ && twin_layer_->should_use_gpu_rasterization() ==
       should_use_gpu_rasterization())
@@ -1166,7 +1167,7 @@
 bool PictureLayerImpl::CanHaveTilings() const {
   if (!DrawsContent())
     return false;
-  if (!pile_->HasRecordings())
+  if (pile_->recorded_region().IsEmpty())
     return false;
   return true;
 }
@@ -1210,6 +1211,11 @@
   state->Set("tilings", tilings_->AsValue().release());
   state->Set("pictures", pile_->AsValue().release());
   state->Set("invalidation", invalidation_.AsValue().release());
+
+  Region unrecorded_region(gfx::Rect(pile_->size()));
+  unrecorded_region.Subtract(pile_->recorded_region());
+  if (!unrecorded_region.IsEmpty())
+    state->Set("unrecorded_region", unrecorded_region.AsValue().release());
 
   scoped_ptr<base::ListValue> coverage_tiles(new base::ListValue);
   for (PictureLayerTilingSet::CoverageIterator iter(tilings_.get(),