Revert "Speculative revert by sheriff"

cc/resources/display_item_list.cc

Index: cc/resources/display_item_list.cc
diff --git a/cc/resources/display_item_list.cc b/cc/resources/display_item_list.cc
index b541c5f34d9a066bf4dfd7fdcbedeca6568850b6..0b2e12e06c1e394e6d934ad70705e5d9c9fcf152 100644
--- a/cc/resources/display_item_list.cc
+++ b/cc/resources/display_item_list.cc
@@ -20,12 +20,36 @@
 
 namespace cc {
 
-DisplayItemList::DisplayItemList()
-    : is_suitable_for_gpu_rasterization_(true), approximate_op_count_(0) {
+DisplayItemList::DisplayItemList(gfx::Rect layer_rect, bool use_cached_picture)
+    : recorder_(new SkPictureRecorder()),
+      use_cached_picture_(use_cached_picture),
+      retain_individual_display_items_(!use_cached_picture),
+      layer_rect_(layer_rect),
+      is_suitable_for_gpu_rasterization_(true),
+      approximate_op_count_(0) {
+  if (use_cached_picture_) {
+    SkRTreeFactory factory;
+    recorder_.reset(new SkPictureRecorder());
+    canvas_ = skia::SharePtr(recorder_->beginRecording(
+        layer_rect_.width(), layer_rect_.height(), &factory));
+    canvas_->translate(-layer_rect_.x(), -layer_rect_.y());
+    canvas_->clipRect(gfx::RectToSkRect(layer_rect_));
+
+    bool tracing_enabled;
+    TRACE_EVENT_CATEGORY_GROUP_ENABLED(
+      TRACE_DISABLED_BY_DEFAULT("cc.debug.picture") ","
+      TRACE_DISABLED_BY_DEFAULT("devtools.timeline.picture"),
+      &tracing_enabled);
+    if (tracing_enabled)
+      retain_individual_display_items_ = true;
+  }
 }
 
-scoped_refptr<DisplayItemList> DisplayItemList::Create() {
-  return make_scoped_refptr(new DisplayItemList());
+scoped_refptr<DisplayItemList> DisplayItemList::Create(
+    gfx::Rect layer_rect,
+    bool use_cached_picture) {
+  return make_scoped_refptr(
+      new DisplayItemList(layer_rect, use_cached_picture));
 }
 
 DisplayItemList::~DisplayItemList() {
@@ -34,7 +58,7 @@ DisplayItemList::~DisplayItemList() {
 void DisplayItemList::Raster(SkCanvas* canvas,
                              SkDrawPictureCallback* callback,
                              float contents_scale) const {
-  if (!picture_) {
+  if (!use_cached_picture_) {
     canvas->save();
     canvas->scale(contents_scale, contents_scale);
     for (size_t i = 0; i < items_.size(); ++i) {
@@ -62,25 +86,25 @@ void DisplayItemList::Raster(SkCanvas* canvas,
 }
 
 void DisplayItemList::CreateAndCacheSkPicture() {
-  // Convert to an SkPicture for faster rasterization. Code is identical to
-  // that in Picture::Record.
-  SkRTreeFactory factory;
-  SkPictureRecorder recorder;
-  skia::RefPtr<SkCanvas> canvas;
-  canvas = skia::SharePtr(recorder.beginRecording(
-      layer_rect_.width(), layer_rect_.height(), &factory));
-  canvas->translate(-layer_rect_.x(), -layer_rect_.y());
-  canvas->clipRect(gfx::RectToSkRect(layer_rect_));
-  for (size_t i = 0; i < items_.size(); ++i)
-    items_[i]->Raster(canvas.get(), NULL);
-  picture_ = skia::AdoptRef(recorder.endRecordingAsPicture());
+  // Convert to an SkPicture for faster rasterization.
+  DCHECK(use_cached_picture_);
+  picture_ = skia::AdoptRef(recorder_->endRecordingAsPicture());
   DCHECK(picture_);
+  recorder_.reset();
+  canvas_.clear();
 }
 
 void DisplayItemList::AppendItem(scoped_ptr<DisplayItem> item) {
   is_suitable_for_gpu_rasterization_ &= item->IsSuitableForGpuRasterization();
   approximate_op_count_ += item->ApproximateOpCount();
-  items_.push_back(item.Pass());
+
+  if (use_cached_picture_) {
+    DCHECK(canvas_);
+    item->Raster(canvas_.get(), NULL);
+  }
+
+  if (retain_individual_display_items_)
+    items_.push_back(item.Pass());
 }
 
 bool DisplayItemList::IsSuitableForGpuRasterization() const {
@@ -126,8 +150,7 @@ DisplayItemList::AsValue() const {
       recorder.beginRecording(layer_rect_.width(), layer_rect_.height());
   canvas->translate(-layer_rect_.x(), -layer_rect_.y());
   canvas->clipRect(gfx::RectToSkRect(layer_rect_));
-  for (size_t i = 0; i < items_.size(); ++i)
-    items_[i]->RasterForTracing(canvas);
+  Raster(canvas, NULL, 1.f);
   skia::RefPtr<SkPicture> picture =
       skia::AdoptRef(recorder.endRecordingAsPicture());