cc: Resource list for headup display

Current HeadUpDisplayLayerImpl allocates one resource
and reuse it continuously. This patch is trying to
allocate two resources and swap one of them
which is available.
so HeadUpDisplayLayerImpl does not need free the resource
while the layer is alive.

Bug=None

Review URL: https://codereview.chromium.org/491783003

Cr-Commit-Position: refs/heads/master@{#292690}

cc/layers/heads_up_display_layer_impl.cc

@@ -81,27 +81,51 @@ scoped_ptr<LayerImpl> HeadsUpDisplayLayerImpl::CreateLayerImpl(
   return HeadsUpDisplayLayerImpl::Create(tree_impl, id()).PassAs<LayerImpl>();
 }
 
-bool HeadsUpDisplayLayerImpl::WillDraw(DrawMode draw_mode,
-                                       ResourceProvider* resource_provider) {
-  if (draw_mode == DRAW_MODE_RESOURCELESS_SOFTWARE)
-    return false;
+void HeadsUpDisplayLayerImpl::AcquireResource(
+    ResourceProvider* resource_provider) {
+  for (ScopedPtrVector<ScopedResource>::iterator it = resources_.begin();
+       it != resources_.end();
+       ++it) {
+    if (!resource_provider->InUseByConsumer((*it)->id())) {
+      resources_.swap(it, resources_.end() - 1);
+      return;
+    }
+  }
 
-  if (!hud_resource_)
-    hud_resource_ = ScopedResource::Create(resource_provider);
+  scoped_ptr<ScopedResource> resource =
+      ScopedResource::Create(resource_provider);
+  resource->Allocate(
+      content_bounds(), ResourceProvider::TextureHintImmutable, RGBA_8888);
+  resources_.push_back(resource.Pass());
+}
 
-  // TODO(danakj): The HUD could swap between two textures instead of creating a
-  // texture every frame in ubercompositor.
-  if (hud_resource_->size() != content_bounds() ||
-      (hud_resource_->id() &&
-       resource_provider->InUseByConsumer(hud_resource_->id()))) {
-    hud_resource_->Free();
-  }
+class ResourceSizeIsEqualTo {
+ public:
+  explicit ResourceSizeIsEqualTo(const gfx::Size& size_)
+      : compare_size_(size_) {}
 
-  if (!hud_resource_->id()) {
-    hud_resource_->Allocate(
-        content_bounds(), ResourceProvider::TextureHintImmutable, RGBA_8888);
+  bool operator()(const ScopedResource* resource) {
+    return resource->size() == compare_size_;
   }
 
+ private:
+  const gfx::Size compare_size_;
+};
+
+void HeadsUpDisplayLayerImpl::ReleaseUnmatchedSizeResources(
+    ResourceProvider* resource_provider) {
+  ScopedPtrVector<ScopedResource>::iterator it_erase =
+      resources_.partition(ResourceSizeIsEqualTo(content_bounds()));
+  resources_.erase(it_erase, resources_.end());
+}
+
+bool HeadsUpDisplayLayerImpl::WillDraw(DrawMode draw_mode,
+                                       ResourceProvider* resource_provider) {
+  if (draw_mode == DRAW_MODE_RESOURCELESS_SOFTWARE)
+    return false;
+
+  ReleaseUnmatchedSizeResources(resource_provider);
+  AcquireResource(resource_provider);
   return LayerImpl::WillDraw(draw_mode, resource_provider);
 }
 
@@ -109,7 +133,7 @@ void HeadsUpDisplayLayerImpl::AppendQuads(
     RenderPass* render_pass,
     const OcclusionTracker<LayerImpl>& occlusion_tracker,
     AppendQuadsData* append_quads_data) {
-  if (!hud_resource_->id())
+  if (!resources_.back()->id())
     return;
 
   SharedQuadState* shared_quad_state =
@@ -130,7 +154,7 @@ void HeadsUpDisplayLayerImpl::AppendQuads(
                quad_rect,
                opaque_rect,
                visible_quad_rect,
-               hud_resource_->id(),
+               resources_.back()->id(),
                premultiplied_alpha,
                uv_top_left,
                uv_bottom_right,
@@ -142,7 +166,7 @@ void HeadsUpDisplayLayerImpl::AppendQuads(
 void HeadsUpDisplayLayerImpl::UpdateHudTexture(
     DrawMode draw_mode,
     ResourceProvider* resource_provider) {
-  if (draw_mode == DRAW_MODE_RESOURCELESS_SOFTWARE || !hud_resource_->id())
+  if (draw_mode == DRAW_MODE_RESOURCELESS_SOFTWARE || !resources_.back()->id())
     return;
 
   SkISize canvas_size;
@@ -179,14 +203,16 @@ void HeadsUpDisplayLayerImpl::UpdateHudTexture(
   DCHECK(pixels);
   gfx::Rect content_rect(content_bounds());
   DCHECK(info.colorType() == kN32_SkColorType);
-  resource_provider->SetPixels(hud_resource_->id(),
+  resource_provider->SetPixels(resources_.back()->id(),
                                static_cast<const uint8_t*>(pixels),
                                content_rect,
                                content_rect,
                                gfx::Vector2d());
 }
 
-void HeadsUpDisplayLayerImpl::ReleaseResources() { hud_resource_.reset(); }
+void HeadsUpDisplayLayerImpl::ReleaseResources() {
+  resources_.clear();
+}
 
 void HeadsUpDisplayLayerImpl::UpdateHudContents() {
   const LayerTreeDebugState& debug_state = layer_tree_impl()->debug_state();

cc/layers/heads_up_display_layer_impl.h

@@ -119,7 +119,10 @@ class CC_EXPORT HeadsUpDisplayLayerImpl : public LayerImpl {
                      const std::string& label_text) const;
   void DrawDebugRects(SkCanvas* canvas, DebugRectHistory* debug_rect_history);
 
-  scoped_ptr<ScopedResource> hud_resource_;
+  void AcquireResource(ResourceProvider* resource_provider);
+  void ReleaseUnmatchedSizeResources(ResourceProvider* resource_provider);
+
+  ScopedPtrVector<ScopedResource> resources_;
   scoped_ptr<SkCanvas> hud_canvas_;
 
   skia::RefPtr<SkTypeface> typeface_;