cc: Document the remaining public and protected methods of cc::Layer

The impl-side SetTrilinearFiltering() is unused, since it is only used
for property tree building, and on the impl-side it comes from the
test properties. So it's removed.

R=weiliangc@chromium.org

Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: Ib9a726dbaa45665a0cd6c585a69e2f7800db78fa
Reviewed-on: https://chromium-review.googlesource.com/1105348
Commit-Queue: danakj <danakj@chromium.org>
Reviewed-by: weiliangc <weiliangc@chromium.org>
Cr-Commit-Position: refs/heads/master@{#568535}

cc/layers/layer.cc

@@ -1230,8 +1230,6 @@ void Layer::PushPropertiesTo(LayerImpl* layer) {
   layer->SetHasWillChangeTransformHint(has_will_change_transform_hint());
   layer->SetNeedsPushProperties();
 
-  layer->SetTrilinearFiltering(trilinear_filtering());
-
   // Reset any state that should be cleared for the next update.
   needs_show_scrollbars_ = false;
   subtree_property_changed_ = false;
@@ -1365,6 +1363,11 @@ void Layer::SetTrilinearFiltering(bool trilinear_filtering) {
   if (inputs_.trilinear_filtering == trilinear_filtering)
     return;
   inputs_.trilinear_filtering = trilinear_filtering;
+  // When true, makes a RenderSurface which makes an effect node.
+  SetPropertyTreesNeedRebuild();
+  // Adding a RenderSurface may change how things in the subtree appear, since
+  // it flattens transforms.
+  SetSubtreePropertyChanged();
   SetNeedsCommit();
 }
 

cc/layers/layer.h

@@ -545,8 +545,6 @@ class CC_EXPORT Layer : public base::RefCounted<Layer> {
   void SetHideLayerAndSubtree(bool hide);
   bool hide_layer_and_subtree() const { return inputs_.hide_layer_and_subtree; }
 
-  void UpdateDebugInfo();
-
   // The index of this layer's node in the various property trees. These are
   // only valid after a main frame, when Update() is called on the layer, and
   // remain valid and in in the same state until the next main frame, or until
@@ -562,6 +560,11 @@ class CC_EXPORT Layer : public base::RefCounted<Layer> {
   void SetHasTransformNode(bool val) { has_transform_node_ = val; }
   bool has_transform_node() { return has_transform_node_; }
 
+  // Sets that the content shown in this layer may be a video. This may be used
+  // by the system compositor to distinguish between animations updating the
+  // screen and video, which the user would be watching. This allows
+  // optimizations like turning off the display when video is not playing,
+  // without interfering with video playback.
   void SetMayContainVideo(bool yes);
 
   // Stable identifier for clients. See comment in cc/trees/element_id.h.
@@ -579,13 +582,15 @@ class CC_EXPORT Layer : public base::RefCounted<Layer> {
     return inputs_.has_will_change_transform_hint;
   }
 
+  // Sets or gets if trilinear filtering should be used to scaling the contents
+  // of this layer and its subtree. When set the layer and its subtree will be
+  // composited together as a single unit, mip maps will be generated of the
+  // subtree together, and trilinear filtering applied when supported, if
+  // scaling during composite of the content from this layer and its subtree
+  // into the target.
   void SetTrilinearFiltering(bool trilinear_filtering);
   bool trilinear_filtering() const { return inputs_.trilinear_filtering; }
 
-  ElementListType GetElementTypeForAnimation() const;
-
-  void SetScrollbarsHiddenFromImplSide(bool hidden);
-
   // Called on the scroll layer to trigger showing the overlay scrollbars.
   void ShowScrollbars() { needs_show_scrollbars_ = true; }
 
@@ -595,6 +600,10 @@ class CC_EXPORT Layer : public base::RefCounted<Layer> {
   // display.
   virtual sk_sp<SkPicture> GetPicture() const;
 
+  // For tracing. Calls out to the LayerClient to get tracing data that will
+  // be attached to this layer's tracing outputs under the 'debug_info' key.
+  void UpdateDebugInfo();
+
   // For telemetry testing. Runs a given test behaviour implemented in
   // |benchmark| for this layer. The base class does nothing as benchmarks
   // only exist for subclass layer types. For each subclass that the
@@ -664,6 +673,11 @@ class CC_EXPORT Layer : public base::RefCounted<Layer> {
   // was called before it.
   void SetNeedsPushProperties();
 
+  // Internal method to call the LayerClient, if there is one, to inform it when
+  // overlay scrollbars have been completely hidden (due to lack of scrolling by
+  // the user).
+  void SetScrollbarsHiddenFromImplSide(bool hidden);
+
   // Internal to property tree construction. A generation number for the
   // property trees, to verify the layer's indices are pointers into the trees
   // currently held by the LayerTreeHost. The number is updated when property
@@ -698,6 +712,11 @@ class CC_EXPORT Layer : public base::RefCounted<Layer> {
   void SetSubtreePropertyChanged();
   bool subtree_property_changed() const { return subtree_property_changed_; }
 
+  // Internal to property tree construction. Returns ElementListType::ACTIVE
+  // as main thread layers do not have a pending/active tree split, and
+  // animations should run normally on the main thread layer tree.
+  ElementListType GetElementTypeForAnimation() const;
+
   // Internal to property tree construction. Whether this layer may animate its
   // opacity on the compositor thread. Layer subclasses may override this to
   // report true. If true, assumptions about opacity can not be made on the main
@@ -735,8 +754,9 @@ class CC_EXPORT Layer : public base::RefCounted<Layer> {
  protected:
   friend class LayerImpl;
   friend class TreeSynchronizer;
-  virtual ~Layer();
+
   Layer();
+  virtual ~Layer();
 
   // These SetNeeds functions are in order of severity of update:
   //
@@ -758,11 +778,18 @@ class CC_EXPORT Layer : public base::RefCounted<Layer> {
   // Will recalculate whether the layer draws content and set draws_content_
   // appropriately.
   void UpdateDrawsContent(bool has_drawable_content);
+  // May be overridden by subclasses if they have optional content, to return
+  // false if there is no content to be displayed. If they do have content, then
+  // they should return the value from this base class method.
   virtual bool HasDrawableContent() const;
 
   // Called when the layer's number of drawable descendants changes.
   void AddDrawableDescendants(int num);
 
+  // For debugging. Returns false if the LayerTreeHost this layer is attached to
+  // is in the process of updating layers for a BeginMainFrame. Layer properties
+  // should be changed by the client before the BeginMainFrame, and should not
+  // be changed while the frame is being generated for commit.
   bool IsPropertyChangeAllowed() const;
 
   // When true, the layer is about to perform an update. Any commit requests

cc/layers/layer_impl.cc

@@ -74,7 +74,6 @@ LayerImpl::LayerImpl(LayerTreeImpl* tree_impl, int id)
       current_draw_mode_(DRAW_MODE_NONE),
       debug_info_(nullptr),
       has_will_change_transform_hint_(false),
-      trilinear_filtering_(false),
       needs_push_properties_(false),
       scrollbars_hidden_(false),
       needs_show_scrollbars_(false),
@@ -101,10 +100,6 @@ void LayerImpl::SetHasWillChangeTransformHint(bool has_will_change) {
   has_will_change_transform_hint_ = has_will_change;
 }
 
-void LayerImpl::SetTrilinearFiltering(bool trilinear_filtering) {
-  trilinear_filtering_ = trilinear_filtering;
-}
-
 ElementListType LayerImpl::GetElementTypeForAnimation() const {
   return IsActive() ? ElementListType::ACTIVE : ElementListType::PENDING;
 }
@@ -325,7 +320,6 @@ void LayerImpl::PushPropertiesTo(LayerImpl* layer) {
   layer->clip_tree_index_ = clip_tree_index_;
   layer->scroll_tree_index_ = scroll_tree_index_;
   layer->has_will_change_transform_hint_ = has_will_change_transform_hint_;
-  layer->trilinear_filtering_ = trilinear_filtering_;
   layer->scrollbars_hidden_ = scrollbars_hidden_;
   if (needs_show_scrollbars_)
     layer->needs_show_scrollbars_ = needs_show_scrollbars_;
@@ -761,8 +755,6 @@ void LayerImpl::AsValueInto(base::trace_event::TracedValue* state) const {
   state->SetBoolean("has_will_change_transform_hint",
                     has_will_change_transform_hint());
 
-  state->SetBoolean("trilinear_filtering", trilinear_filtering());
-
   MainThreadScrollingReason::AddToTracedValue(main_thread_scrolling_reasons_,
                                               *state);
 

cc/layers/layer_impl.h

@@ -430,9 +430,6 @@ class CC_EXPORT LayerImpl {
     return has_will_change_transform_hint_;
   }
 
-  void SetTrilinearFiltering(bool trilinear_filtering);
-  bool trilinear_filtering() const { return trilinear_filtering_; }
-
   ElementListType GetElementTypeForAnimation() const;
 
   void set_needs_show_scrollbars(bool yes) { needs_show_scrollbars_ = yes; }
@@ -567,7 +564,6 @@ class CC_EXPORT LayerImpl {
   base::trace_event::TracedValue* debug_info_;
 
   bool has_will_change_transform_hint_ : 1;
-  bool trilinear_filtering_ : 1;
   bool needs_push_properties_ : 1;
   bool scrollbars_hidden_ : 1;
 

cc/layers/layer_unittest.cc

@@ -337,6 +337,22 @@ TEST_F(LayerTest, LayerPropertyChangedForSubtree) {
       child2->PushPropertiesTo(child2_impl.get());
       grand_child->PushPropertiesTo(grand_child_impl.get()));
 
+  EXPECT_CALL(*layer_tree_host_, SetNeedsCommit()).Times(1);
+  EXECUTE_AND_VERIFY_SUBTREE_CHANGED(root->SetTrilinearFiltering(true));
+  EXECUTE_AND_VERIFY_SUBTREE_CHANGES_RESET(
+      root->PushPropertiesTo(root_impl.get());
+      child->PushPropertiesTo(child_impl.get());
+      child2->PushPropertiesTo(child2_impl.get());
+      grand_child->PushPropertiesTo(grand_child_impl.get()));
+
+  EXPECT_CALL(*layer_tree_host_, SetNeedsCommit()).Times(1);
+  EXECUTE_AND_VERIFY_SUBTREE_CHANGED(root->SetTrilinearFiltering(false));
+  EXECUTE_AND_VERIFY_SUBTREE_CHANGES_RESET(
+      root->PushPropertiesTo(root_impl.get());
+      child->PushPropertiesTo(child_impl.get());
+      child2->PushPropertiesTo(child2_impl.get());
+      grand_child->PushPropertiesTo(grand_child_impl.get()));
+
   EXPECT_CALL(*layer_tree_host_, SetNeedsCommit()).Times(1);
   EXECUTE_AND_VERIFY_SUBTREE_CHANGED(root->SetDoubleSided(false));
   EXECUTE_AND_VERIFY_SUBTREE_CHANGES_RESET(