Fix shadow layer not being updated correctly when recreated.

BUG=988530
TEST=Manually

Change-Id: Ifbd2b8184490b14e146bb822791347de4b36a975
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1724121
Commit-Queue: Ahmed Fakhry <afakhry@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#682358}

ui/compositor_extra/shadow.cc

@@ -19,9 +19,9 @@ constexpr int kShadowAnimationDurationMs = 100;
 
 }  // namespace
 
-Shadow::Shadow() {}
+Shadow::Shadow() : shadow_layer_owner_(this) {}
 
-Shadow::~Shadow() {}
+Shadow::~Shadow() = default;
 
 void Shadow::Init(int elevation) {
   DCHECK_GE(elevation, 0);
@@ -91,17 +91,33 @@ void Shadow::OnImplicitAnimationsCompleted() {
   UpdateLayerBounds();
 }
 
+// -----------------------------------------------------------------------------
+// Shadow::ShadowLayerOwner:
+
+Shadow::ShadowLayerOwner::ShadowLayerOwner(Shadow* owner,
+                                           std::unique_ptr<Layer> layer)
+    : LayerOwner(std::move(layer)), owner_shadow_(owner) {}
+
+Shadow::ShadowLayerOwner::~ShadowLayerOwner() = default;
+
+std::unique_ptr<Layer> Shadow::ShadowLayerOwner::RecreateLayer() {
+  auto result = ui::LayerOwner::RecreateLayer();
+  // Now update the newly recreated shadow layer with the correct nine patch
+  // image details.
+  owner_shadow_->details_ = nullptr;
+  owner_shadow_->UpdateLayerBounds();
+  return result;
+}
+
+// -----------------------------------------------------------------------------
+// Shadow:
+
 void Shadow::RecreateShadowLayer() {
-  if (shadow_layer_owner_.OwnsLayer()) {
-    shadow_layer_owner_.RecreateLayer();
-  } else {
-    shadow_layer_owner_.Reset(
-        std::make_unique<ui::Layer>(ui::LAYER_NINE_PATCH));
+  shadow_layer_owner_.Reset(std::make_unique<ui::Layer>(ui::LAYER_NINE_PATCH));
   shadow_layer()->set_name("Shadow");
   shadow_layer()->SetVisible(true);
   shadow_layer()->SetFillsBoundsOpaquely(false);
   layer()->Add(shadow_layer());
-  }
 
   UpdateLayerBounds();
 }

ui/compositor_extra/shadow.h

@@ -57,6 +57,23 @@ class Shadow : public ui::ImplicitAnimationObserver, public ui::LayerOwner {
   void OnImplicitAnimationsCompleted() override;
 
  private:
+  // A shadow layer owner that correctly updates the nine patch layer details
+  // when it gets recreated.
+  class ShadowLayerOwner : public ui::LayerOwner {
+   public:
+    explicit ShadowLayerOwner(Shadow* owner,
+                              std::unique_ptr<Layer> layer = nullptr);
+    ~ShadowLayerOwner() override;
+
+    // ui::LayerOwner:
+    std::unique_ptr<Layer> RecreateLayer() override;
+
+   private:
+    Shadow* const owner_shadow_;
+
+    DISALLOW_COPY_AND_ASSIGN(ShadowLayerOwner);
+  };
+
   // Updates the shadow layer and its image to reflect |desired_elevation_|.
   void RecreateShadowLayer();
 
@@ -82,7 +99,7 @@ class Shadow : public ui::ImplicitAnimationObserver, public ui::LayerOwner {
   const gfx::ShadowDetails* details_ = nullptr;
 
   // The owner of the actual shadow layer corresponding to a cc::NinePatchLayer.
-  ui::LayerOwner shadow_layer_owner_;
+  ShadowLayerOwner shadow_layer_owner_;
 
   // When the elevation changes, the old shadow cross-fades with the new one.
   // When non-null, this owns an old |shadow_layer()| that's being animated out.