aura: Allow delegated frames to be used by more than one impl layer.

cc/layers/delegated_renderer_layer_impl.cc

Index: cc/layers/delegated_renderer_layer_impl.cc
diff --git a/cc/layers/delegated_renderer_layer_impl.cc b/cc/layers/delegated_renderer_layer_impl.cc
index 34a1cd86755949fbe946dba7057a7fc647aba072..a40246ec196bbe642064f6c84a6f7ec7500c7deb 100644
--- a/cc/layers/delegated_renderer_layer_impl.cc
+++ b/cc/layers/delegated_renderer_layer_impl.cc
@@ -33,9 +33,7 @@ DelegatedRendererLayerImpl::~DelegatedRendererLayerImpl() {
   ClearChildId();
 }
 
-bool DelegatedRendererLayerImpl::HasDelegatedContent() const {
-  return !render_passes_in_draw_order_.empty();
-}
+bool DelegatedRendererLayerImpl::HasDelegatedContent() const { return true; }
 
 bool DelegatedRendererLayerImpl::HasContributingDelegatedRenderPasses() const {
   // The root RenderPass for the layer is merged with its target
@@ -101,14 +99,13 @@ void DelegatedRendererLayerImpl::CreateChildIdIfNeeded(
 }
 
 void DelegatedRendererLayerImpl::SetFrameData(
-    scoped_ptr<DelegatedFrameData> frame_data,
+    const DelegatedFrameData* frame_data,
     gfx::RectF damage_in_frame) {
-  DCHECK(frame_data);
   DCHECK(child_id_) << "CreateChildIdIfNeeded must be called first.";
-
+  DCHECK(frame_data);
+  DCHECK_NE(0u, frame_data->render_pass_list.size());
   // A frame with an empty root render pass is invalid.
-  DCHECK(frame_data->render_pass_list.empty() ||
-         !frame_data->render_pass_list.back()->output_rect.IsEmpty());
+  DCHECK(!frame_data->render_pass_list.back()->output_rect.IsEmpty());
 
   ResourceProvider* resource_provider = layer_tree_impl()->resource_provider();
     const ResourceProvider::ResourceIdMap& resource_map =
@@ -116,6 +113,9 @@ void DelegatedRendererLayerImpl::SetFrameData(
 
   resource_provider->ReceiveFromChild(child_id_, frame_data->resource_list);
 
+  ScopedPtrVector<RenderPass> render_pass_list;
+  RenderPass::CopyAll(frame_data->render_pass_list, &render_pass_list);
+
   bool invalid_frame = false;
   ResourceProvider::ResourceIdArray resources_in_frame;
   DrawQuad::ResourceIteratorCallback remap_resources_to_parent_callback =
@@ -123,8 +123,8 @@ void DelegatedRendererLayerImpl::SetFrameData(
                  &invalid_frame,
                  resource_map,
                  &resources_in_frame);
-  for (size_t i = 0; i < frame_data->render_pass_list.size(); ++i) {
-    RenderPass* pass = frame_data->render_pass_list[i];
+  for (size_t i = 0; i < render_pass_list.size(); ++i) {
+    RenderPass* pass = render_pass_list[i];
     for (size_t j = 0; j < pass->quad_list.size(); ++j) {
       DrawQuad* quad = pass->quad_list[j];
       quad->IterateResources(remap_resources_to_parent_callback);
@@ -143,18 +143,13 @@ void DelegatedRendererLayerImpl::SetFrameData(
 
   // Display size is already set so we can compute what the damage rect
   // will be in layer space.
-  if (!frame_data->render_pass_list.empty()) {
-    RenderPass* new_root_pass = frame_data->render_pass_list.back();
-    gfx::RectF damage_in_layer = MathUtil::MapClippedRect(
-        DelegatedFrameToLayerSpaceTransform(
-            new_root_pass->output_rect.size()),
-        damage_in_frame);
-    set_update_rect(gfx::UnionRects(update_rect(), damage_in_layer));
-  }
+  RenderPass* new_root_pass = render_pass_list.back();
+  gfx::Size frame_size = new_root_pass->output_rect.size();
+  gfx::RectF damage_in_layer = MathUtil::MapClippedRect(
+      DelegatedFrameToLayerSpaceTransform(frame_size), damage_in_frame);
+  set_update_rect(gfx::UnionRects(update_rect(), damage_in_layer));
 
-  // Save the remapped quads on the layer. This steals the quads and render
-  // passes from the frame_data.
-  SetRenderPasses(&frame_data->render_pass_list);
+  SetRenderPasses(&render_pass_list);
   have_render_passes_to_push_ = true;
 }
 
@@ -184,7 +179,6 @@ void DelegatedRendererLayerImpl::SetRenderPasses(
 }
 
 void DelegatedRendererLayerImpl::ClearRenderPasses() {
-  // TODO(danakj): Release the resources back to the nested compositor.
   render_passes_index_by_id_.clear();
   render_passes_in_draw_order_.clear();
 }
@@ -271,6 +265,7 @@ void DelegatedRendererLayerImpl::AppendQuads(
     AppendQuadsData* append_quads_data) {
   AppendRainbowDebugBorder(quad_sink, append_quads_data);
 
+  // This list will be empty after a lost context until a new frame arrives.
   if (render_passes_in_draw_order_.empty())
     return;