Handle ui::Layer's visibility using cc::Layer's m_isDrawable flag

ui/compositor/layer.cc

Index: ui/compositor/layer.cc
diff --git a/ui/compositor/layer.cc b/ui/compositor/layer.cc
index 119a1cfa868390103209691c432da434f32c665f..cdcf3392e754823924a17f8d11c3c73627063875 100644
--- a/ui/compositor/layer.cc
+++ b/ui/compositor/layer.cc
@@ -134,6 +134,7 @@ void Layer::Add(Layer* child) {
   children_.push_back(child);
   cc_layer_->addChild(child->cc_layer_);
   child->OnDeviceScaleFactorChanged(device_scale_factor_);
+  child->OnParentIsDrawnChanged(IsDrawn(), true);

[piman, 2013/01/31 23:21:59]

If we are going to propagate the information down, could we then store it and
make IsDrawn() non recursive?

[ajuma, 2013/02/01 16:04:06]

Done.

 }
 
 void Layer::Remove(Layer* child) {
@@ -373,6 +374,19 @@ bool Layer::IsDrawn() const {
   return layer == NULL;
 }
 
+void Layer::OnParentIsDrawnChanged(bool parent_is_drawn, bool force_update) {
+  if (!visible_ && !force_update)
+    return;
+
+  cc_layer_->setIsDrawable(
+      visible_ && parent_is_drawn && type_ != LAYER_NOT_DRAWN);
+
+  for (size_t i = 0; i < children_.size(); ++i) {
+    children_[i]->OnParentIsDrawnChanged(visible_ && parent_is_drawn,
+                                         force_update);
+  }
+}
+
 bool Layer::ShouldDraw() const {
   return type_ != LAYER_NOT_DRAWN && GetCombinedOpacity() > 0.0f;
 }
@@ -438,9 +452,9 @@ void Layer::SetExternalTexture(Texture* texture) {
     }
     cc_layer_->setAnchorPoint(gfx::PointF());
     cc_layer_->setContentsOpaque(fills_bounds_opaquely_);
-    cc_layer_->setOpacity(visible_ ? opacity_ : 0.f);
+    cc_layer_->setOpacity(opacity_);
     cc_layer_->setForceRenderSurface(force_render_surface_);
-    cc_layer_->setIsDrawable(true);
+    cc_layer_->setIsDrawable(IsDrawn());
     RecomputeTransform();
   }
   RecomputeDrawsContentAndUVRect();
@@ -645,8 +659,7 @@ void Layer::SetOpacityImmediately(float opacity) {
   bool schedule_draw = (opacity != opacity_ && IsDrawn());
   opacity_ = opacity;
 
-  if (visible_)
-    cc_layer_->setOpacity(opacity);
+  cc_layer_->setOpacity(opacity);
   if (schedule_draw)
     ScheduleDraw();
 }
@@ -656,8 +669,13 @@ void Layer::SetVisibilityImmediately(bool visible) {
     return;
 
   visible_ = visible;
-  // TODO(piman): Expose a visibility flag on WebLayer.
-  cc_layer_->setOpacity(visible_ ? opacity_ : 0.f);
+
+  if (parent_ && !parent_->IsDrawn())
+    return;
+
+  cc_layer_->setIsDrawable(visible_ && type_ != LAYER_NOT_DRAWN);
+  for (size_t i = 0; i < children_.size(); ++i)
+    children_[i]->OnParentIsDrawnChanged(visible_, false);

[piman, 2013/01/31 23:21:59]

Can we share that code with OnParentIsDrawnChanged? In particular the logic for
what we pass to setIsDrawable would benefit from being specified only once.

[ajuma, 2013/02/01 16:04:06]

Done. The logic is now specified only in UpdateIsDrawn.

 }
 
 void Layer::SetBrightnessImmediately(float brightness) {