Allow layers to signal that additional sequences are needed before surface destruction

cc/layers/surface_layer.cc

Index: cc/layers/surface_layer.cc
diff --git a/cc/layers/surface_layer.cc b/cc/layers/surface_layer.cc
index ba577a00d58e7abd952b794ed1dd04d8f98640d3..2d8b0e1baff7d54a766aada5bac2114ae688dc03 100644
--- a/cc/layers/surface_layer.cc
+++ b/cc/layers/surface_layer.cc
@@ -4,10 +4,48 @@
 
 #include "cc/layers/surface_layer.h"
 
+#include "cc/base/swap_promise.h"
 #include "cc/layers/surface_layer_impl.h"
+#include "cc/surfaces/surface_manager.h"
+#include "cc/trees/layer_tree_host.h"
 
 namespace cc {
 
+// This only works with threaded compositing disabled, as the swap promise could
+// be destroyed on either the impl or main thread.
+class SatisfySwapPromise : public SwapPromise,
+                           public base::SupportsWeakPtr<SatisfySwapPromise> {
+ public:
+  SatisfySwapPromise(SurfaceSequence sequence,
+                     LayerTreeHost* host,
+                     SurfaceHolder::SatisfyCallback satisfy_callback)
+      : sequence_(sequence), host_(host), satisfy_callback_(satisfy_callback) {}
+
+  SurfaceSequence RemoveSequence() {
+    SurfaceSequence last_sequence = sequence_;
+    sequence_ = SurfaceSequence();
+    return last_sequence;
+  }
+
+  LayerTreeHost* host() { return host_; }
+
+ private:
+  void DidSwap(CompositorFrameMetadata* metadata) override {
+    if (!sequence_.is_null())
+      metadata->satisfies_sequences.push_back(sequence_.sequence);
+  }
+
+  void DidNotSwap(DidNotSwapReason reason) override {
+    if (!sequence_.is_null())
+      satisfy_callback_.Run(sequence_);
+  }
+  int64 TraceId() const override { return 0; }
+
+  SurfaceSequence sequence_;
+  LayerTreeHost* host_;
+  SurfaceHolder::SatisfyCallback satisfy_callback_;
+};
+
 scoped_refptr<SurfaceLayer> SurfaceLayer::Create() {
   return make_scoped_refptr(new SurfaceLayer);
 }
@@ -15,10 +53,17 @@ scoped_refptr<SurfaceLayer> SurfaceLayer::Create() {
 SurfaceLayer::SurfaceLayer() : Layer() {
 }
 
-SurfaceLayer::~SurfaceLayer() {}
+SurfaceLayer::~SurfaceLayer() {
+  DCHECK(!layer_tree_host());
+  DCHECK(destroy_sequence_.is_null());
+}
+
+void SurfaceLayer::SetSurfaceId(scoped_refptr<SurfaceHolder> surface_holder) {
+  SatisfyDestroySequence();
+  surface_holder_ = surface_holder;
+  last_swap_promise_.reset();
+  CreateNewDestroySequence();
 
-void SurfaceLayer::SetSurfaceId(SurfaceId surface_id) {
-  surface_id_ = surface_id;
   UpdateDrawsContent(HasDrawableContent());
   SetNeedsPushProperties();
 }
@@ -28,14 +73,58 @@ scoped_ptr<LayerImpl> SurfaceLayer::CreateLayerImpl(LayerTreeImpl* tree_impl) {
 }
 
 bool SurfaceLayer::HasDrawableContent() const {
-  return !surface_id_.is_null() && Layer::HasDrawableContent();
+  return surface_holder_.get() && !surface_holder_->surface_id().is_null() &&
+         Layer::HasDrawableContent();
+}
+
+void SurfaceLayer::SetLayerTreeHost(LayerTreeHost* host) {
+  if (layer_tree_host() == host) {
+    Layer::SetLayerTreeHost(host);
+    return;
+  }
+
+  SatisfyDestroySequence();
+  Layer::SetLayerTreeHost(host);
+  CreateNewDestroySequence();
 }
 
 void SurfaceLayer::PushPropertiesTo(LayerImpl* layer) {
   Layer::PushPropertiesTo(layer);
   SurfaceLayerImpl* layer_impl = static_cast<SurfaceLayerImpl*>(layer);
 
-  layer_impl->SetSurfaceId(surface_id_);
+  layer_impl->SetSurfaceId(surface_holder_.get() ? surface_holder_->surface_id()
+                                                 : SurfaceId());
+}
+
+void SurfaceLayer::CreateNewDestroySequence() {
+  DCHECK(destroy_sequence_.is_null());
+  if (layer_tree_host() && surface_holder_.get()) {
+    if (last_swap_promise_ && last_swap_promise_->host() == layer_tree_host()) {
+      // Last swap promise hasn't been submitted yet, so reuse its
+      // SurfaceSequence instead of creating a new one. This allows the layer
+      // to be removed from and added back to a tree in the course of a commit
+      // and avoid requiring a new sequence.
+      destroy_sequence_ = last_swap_promise_->RemoveSequence();
+      DCHECK(!destroy_sequence_.is_null());
+      last_swap_promise_.reset();
+    } else {
+      destroy_sequence_ = layer_tree_host()->CreateSurfaceSequence();
+      surface_holder_->AddSurfaceSequence(destroy_sequence_);
+    }
+  }
+}
+
+void SurfaceLayer::SatisfyDestroySequence() {
+  if (!layer_tree_host() || !surface_holder_.get())
+    return;
+  DCHECK(!destroy_sequence_.is_null());
+  scoped_ptr<SatisfySwapPromise> satisfy(
+      new SatisfySwapPromise(destroy_sequence_,
+                             layer_tree_host(),
+                             surface_holder_->satisfy_callback()));
+  last_swap_promise_ = satisfy->AsWeakPtr();
+  layer_tree_host()->QueueSwapPromise(satisfy.Pass());
+  destroy_sequence_ = SurfaceSequence();
 }
 
 }  // namespace cc