Generalize layer mirroring for phantom windows

ui/compositor/layer.cc

Index: ui/compositor/layer.cc
diff --git a/ui/compositor/layer.cc b/ui/compositor/layer.cc
index ac20550710eff3c762a72a6000170a9b61ae6ae6..6da6f9109533a3136ada87ac64bb52b2754fa674 100644
--- a/ui/compositor/layer.cc
+++ b/ui/compositor/layer.cc
@@ -28,7 +28,6 @@
 #include "ui/compositor/compositor_switches.h"
 #include "ui/compositor/dip_util.h"
 #include "ui/compositor/layer_animator.h"
-#include "ui/compositor/layer_observer.h"
 #include "ui/compositor/paint_context.h"
 #include "ui/gfx/animation/animation.h"
 #include "ui/gfx/canvas.h"
@@ -96,6 +95,9 @@ Layer::Layer(LayerType type)
 }
 
 Layer::~Layer() {
+  for (auto* mirror : mirrors_)
+    mirror->RemoveObserver(this);
+
   for (auto& observer : observer_list_)
     observer.LayerDestroyed(this);
 
@@ -119,6 +121,37 @@ Layer::~Layer() {
     mailbox_release_callback_->Run(gpu::SyncToken(), false);
 }
 
+std::unique_ptr<Layer> Layer::Clone() const {
+  auto clone = base::MakeUnique<Layer>(type_);
+
+  clone->SetVisible(GetTargetVisibility());
+  clone->SetOpacity(GetTargetOpacity());

[sky, 2016/10/14 22:36:37]

What about
int background_blur_radius_, satuations, brightness, grayscale, inverted, mask,
zoom...?

ALso, how about changing the name of the clone to be name_ + "clone" ?

[Dominik Laskowski, 2016/10/17 19:53:21]

This code was pulled from LayerOwner::RecreateLayer, so this subset was
apparently sufficient. Anyway, I've updated it to copy the remaining Layer
state. The cc::Layer content isn't copied for all layer types, but this patch is
only intended for surface mirroring, so I've added a cautionary comment for now.

Based on a quick code search, the convention is to delimit layer names with
colons, so I've changed the name accordingly.

+  clone->SetBounds(bounds_);
+  clone->SetMasksToBounds(GetMasksToBounds());
+  clone->set_name(name_);
+  clone->SetFillsBoundsOpaquely(fills_bounds_opaquely_);
+  clone->SetFillsBoundsCompletely(fills_bounds_completely_);
+  clone->SetSubpixelPositionOffset(subpixel_position_offset_);
+  clone->SetLayerInverted(layer_inverted_);
+  clone->SetTransform(GetTargetTransform());
+
+  if (type_ == LAYER_SOLID_COLOR)
+    clone->SetColor(GetTargetColor());
+  if (alpha_shape_)
+    clone->SetAlphaShape(base::MakeUnique<SkRegion>(*alpha_shape_));
+
+  if (surface_layer_ && !surface_layer_->surface_id().is_null()) {
+    clone->SetShowSurface(
+        surface_layer_->surface_id(),
+        surface_layer_->satisfy_callback(),
+        surface_layer_->require_callback(),
+        surface_layer_->surface_size(),
+        surface_layer_->surface_scale(),
+        frame_size_in_dip_);
+  }
+  return clone;
+}
+
 const Compositor* Layer::GetCompositor() const {
   return GetRoot(this)->compositor_;
 }
@@ -593,8 +626,17 @@ void Layer::SetShowSurface(
   frame_size_in_dip_ = frame_size_in_dip;
   RecomputeDrawsContentAndUVRect();
 
-  for (auto& observer : observer_list_)
-    observer.SurfaceChanged(this);
+  for (auto* mirror : mirrors_) {
+    mirror->SetShowSurface(surface_id, satisfy_callback, require_callback,
+                           surface_size, scale, frame_size_in_dip);
+  }
+}
+
+std::unique_ptr<Layer> Layer::Mirror() {
+  std::unique_ptr<Layer> mirror = Clone();
+  mirror->AddObserver(this);
+  mirrors_.push_back(mirror.get());
+  return mirror;
 }
 
 void Layer::SetShowSolidColorContent() {
@@ -651,9 +693,10 @@ void Layer::UpdateNinePatchOcclusion(const gfx::Rect& occlusion) {
 
 void Layer::SetColor(SkColor color) { GetAnimator()->SetColor(color); }
 
-SkColor Layer::GetTargetColor() {
-  if (GetAnimator()->IsAnimatingProperty(LayerAnimationElement::COLOR))
-    return GetAnimator()->GetTargetColor();
+SkColor Layer::GetTargetColor() const {
+  if (animator_.get() && animator_->IsAnimatingProperty(
+      LayerAnimationElement::COLOR))
+    return animator_->GetTargetColor();
   return cc_layer_->background_color();
 }
 
@@ -916,6 +959,11 @@ void Layer::SetBoundsFromAnimation(const gfx::Rect& bounds) {
     // Always schedule a paint, even if we're invisible.
     SchedulePaint(gfx::Rect(bounds.size()));
   }
+
+  if (sync_bounds_) {
+    for (auto* mirror : mirrors_)
+      mirror->SetBounds(bounds);
+  }
 }
 
 void Layer::SetTransformFromAnimation(const gfx::Transform& transform) {
@@ -1005,6 +1053,12 @@ LayerThreadedAnimationDelegate* Layer::GetThreadedAnimationDelegate() {
   return animator_.get();
 }
 
+void Layer::LayerDestroyed(Layer* mirror) {
+  const auto it = std::find(mirrors_.begin(), mirrors_.end(), mirror);
+  DCHECK(it != mirrors_.end());
+  mirrors_.erase(it);
+}
+
 void Layer::CreateCcLayer() {
   if (type_ == LAYER_SOLID_COLOR) {
     solid_color_layer_ = cc::SolidColorLayer::Create();