Make cc::Layer's scroll offset for layer tree mode only

cc::Layer's scroll offset should just for layer tree mode as the input
of cc::PropertyTreeBuilder. In layer list mode, blink generates all
paint properties, and cc should use the paint properties instead of
the layer properties.

(TBR for a trivial change under compositor/ui/layer.cc due to rename
 of cc::Layer::paint_offset)
TBR=wangxianzhu@chromium.org

Change-Id: I5865e4a98f0c4c6957ed117b9de189fd7bd84a00
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2020554
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Reviewed-by: Philip Rogers <pdr@chromium.org>
Reviewed-by: David Bokan <bokan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#737560}

cc/input/scrollbar_animation_controller_unittest.cc

@@ -87,11 +87,10 @@ class ScrollbarAnimationControllerAuraOverlayTest
     clip_layer_ = root_layer();
     clip_layer_->SetBounds(gfx::Size(100, 100));
 
-    scroll_layer_->SetScrollable(gfx::Size(100, 100));
     scroll_layer_->SetBounds(gfx::Size(200, 200));
     CopyProperties(clip_layer_, scroll_layer_);
     CreateTransformNode(scroll_layer_);
-    CreateScrollNode(scroll_layer_);
+    CreateScrollNode(scroll_layer_, gfx::Size(100, 100));
 
     v_scrollbar_layer_->SetBounds(gfx::Size(kThumbThickness, kTrackLength));
     v_scrollbar_layer_->SetScrollElementId(scroll_layer_->element_id());
@@ -171,16 +170,16 @@ TEST_F(ScrollbarAnimationControllerAuraOverlayTest, AppearOnResize) {
 
   // Make the Layer non-scrollable, scrollbar disappears.
   clip_layer_->SetBounds(gfx::Size(200, 200));
-  scroll_layer_->SetScrollable(gfx::Size(200, 200));
   GetScrollNode(scroll_layer_)->container_bounds = gfx::Size(200, 200);
+  scroll_layer_->UpdateScrollable();
   UpdateActiveTreeDrawProperties();
   scrollbar_controller_->DidScrollUpdate();
   ExpectScrollbarsOpacity(0);
 
   // Make the layer scrollable, scrollbar appears again.
   clip_layer_->SetBounds(gfx::Size(100, 100));
-  scroll_layer_->SetScrollable(gfx::Size(100, 100));
   GetScrollNode(scroll_layer_)->container_bounds = gfx::Size(100, 100);
+  scroll_layer_->UpdateScrollable();
   UpdateActiveTreeDrawProperties();
   scrollbar_controller_->DidScrollUpdate();
   ExpectScrollbarsOpacity(1);
@@ -196,8 +195,8 @@ TEST_F(ScrollbarAnimationControllerAuraOverlayTest, HideOnResize) {
   // Shrink along X axis, horizontal scrollbar should appear.
   clip_layer_->SetBounds(gfx::Size(100, 200));
   EXPECT_EQ(gfx::Size(100, 200), clip_layer_->bounds());
-  scroll_layer_->SetScrollable(gfx::Size(100, 200));
   GetScrollNode(scroll_layer_)->container_bounds = gfx::Size(100, 200);
+  scroll_layer_->UpdateScrollable();
   UpdateActiveTreeDrawProperties();
 
   scrollbar_controller_->DidScrollBegin();
@@ -211,8 +210,8 @@ TEST_F(ScrollbarAnimationControllerAuraOverlayTest, HideOnResize) {
   // should disappear.
   clip_layer_->SetBounds(gfx::Size(200, 100));
   EXPECT_EQ(gfx::Size(200, 100), clip_layer_->bounds());
-  scroll_layer_->SetScrollable(gfx::Size(200, 100));
   GetScrollNode(scroll_layer_)->container_bounds = gfx::Size(200, 100);
+  scroll_layer_->UpdateScrollable();
   UpdateActiveTreeDrawProperties();
 
   scrollbar_controller_->DidScrollBegin();
@@ -1386,10 +1385,9 @@ class ScrollbarAnimationControllerAndroidTest
     SetElementIdsForTesting();
 
     scroll_layer_->SetBounds(gfx::Size(200, 200));
-    scroll_layer_->SetScrollable(gfx::Size(100, 100));
     CopyProperties(root, scroll_layer_);
     CreateTransformNode(scroll_layer_);
-    CreateScrollNode(scroll_layer_);
+    CreateScrollNode(scroll_layer_, gfx::Size(100, 100));
 
     scrollbar_layer_->SetScrollElementId(scroll_layer_->element_id());
     CopyProperties(scroll_layer_, scrollbar_layer_);
@@ -1472,8 +1470,8 @@ TEST_F(ScrollbarAnimationControllerAndroidTest, HideOnResize) {
   EXPECT_EQ(HORIZONTAL, scrollbar_layer_->orientation());
 
   // Shrink along X axis, horizontal scrollbar should appear.
-  scroll_layer_->SetScrollable(gfx::Size(100, 200));
   GetScrollNode(scroll_layer_)->container_bounds = gfx::Size(100, 200);
+  scroll_layer_->UpdateScrollable();
   UpdateActiveTreeDrawProperties();
   scrollbar_controller_->DidScrollBegin();
 
@@ -1483,8 +1481,8 @@ TEST_F(ScrollbarAnimationControllerAndroidTest, HideOnResize) {
 
   // Shrink along Y axis and expand along X, horizontal scrollbar
   // should disappear.
-  scroll_layer_->SetScrollable(gfx::Size(200, 100));
   GetScrollNode(scroll_layer_)->container_bounds = gfx::Size(200, 100);
+  scroll_layer_->UpdateScrollable();
   UpdateActiveTreeDrawProperties();
 
   scrollbar_controller_->DidScrollBegin();
@@ -1501,8 +1499,8 @@ TEST_F(VerticalScrollbarAnimationControllerAndroidTest, HideOnResize) {
   EXPECT_EQ(VERTICAL, scrollbar_layer_->orientation());
 
   // Shrink along X axis, vertical scrollbar should remain invisible.
-  scroll_layer_->SetScrollable(gfx::Size(100, 200));
   GetScrollNode(scroll_layer_)->container_bounds = gfx::Size(100, 200);
+  scroll_layer_->UpdateScrollable();
   UpdateActiveTreeDrawProperties();
   scrollbar_controller_->DidScrollBegin();
 
@@ -1511,8 +1509,8 @@ TEST_F(VerticalScrollbarAnimationControllerAndroidTest, HideOnResize) {
   scrollbar_controller_->DidScrollEnd();
 
   // Shrink along Y axis and expand along X, vertical scrollbar should appear.
-  scroll_layer_->SetScrollable(gfx::Size(200, 100));
   GetScrollNode(scroll_layer_)->container_bounds = gfx::Size(200, 100);
+  scroll_layer_->UpdateScrollable();
   UpdateActiveTreeDrawProperties();
 
   scrollbar_controller_->DidScrollBegin();

cc/input/scrollbar_controller.cc

@@ -403,17 +403,10 @@ float ScrollbarController::GetScrollerToScrollbarRatio(
       scrollbar->orientation() == ScrollbarOrientation::VERTICAL
           ? thumb_rect.height()
           : thumb_rect.width();
+  int viewport_length = GetViewportLength(scrollbar);
 
-  const LayerImpl* owner_scroll_layer =
-      layer_tree_host_impl_->active_tree()->ScrollableLayerByElementId(
-          scrollbar->scroll_element_id());
-  const float viewport_length =
-      scrollbar->orientation() == ScrollbarOrientation::VERTICAL
-          ? owner_scroll_layer->scroll_container_bounds().height()
-          : (owner_scroll_layer->scroll_container_bounds().width());
-
-  return ((scroll_layer_length - viewport_length) /
-          (scrollbar_track_length - scrollbar_thumb_length));
+  return (scroll_layer_length - viewport_length) /
+         (scrollbar_track_length - scrollbar_thumb_length);
 }
 
 void ScrollbarController::ResetState() {
@@ -597,34 +590,39 @@ LayerImpl* ScrollbarController::GetLayerHitByPoint(
   return layer_impl;
 }
 
+int ScrollbarController::GetViewportLength(
+    const ScrollbarLayerImplBase* scrollbar) const {
+  const ScrollNode* scroll_node =
+      layer_tree_host_impl_->active_tree()
+          ->property_trees()
+          ->scroll_tree.FindNodeFromElementId(scrollbar->scroll_element_id());
+  DCHECK(scroll_node);
+  return scrollbar->orientation() == ScrollbarOrientation::VERTICAL
+             ? scroll_node->container_bounds.height()
+             : scroll_node->container_bounds.width();
+}
+
 int ScrollbarController::GetScrollDeltaForScrollbarPart(
     const ScrollbarLayerImplBase* scrollbar,
     const ScrollbarPart scrollbar_part,
     const bool shift_modifier) {
   int scroll_delta = 0;
-  int viewport_length = 0;
-  LayerImpl* owner_scroll_layer = nullptr;
 
   switch (scrollbar_part) {
     case ScrollbarPart::BACK_BUTTON:
     case ScrollbarPart::FORWARD_BUTTON:
       scroll_delta = kPixelsPerLineStep * ScreenSpaceScaleFactor();
       break;
     case ScrollbarPart::BACK_TRACK:
-    case ScrollbarPart::FORWARD_TRACK:
+    case ScrollbarPart::FORWARD_TRACK: {
       if (shift_modifier) {
         scroll_delta = GetScrollDeltaForAbsoluteJump(scrollbar);
         break;
       }
-      owner_scroll_layer =
-          layer_tree_host_impl_->active_tree()->ScrollableLayerByElementId(
-              scrollbar->scroll_element_id());
-      viewport_length =
-          scrollbar->orientation() == ScrollbarOrientation::VERTICAL
-              ? owner_scroll_layer->scroll_container_bounds().height()
-              : (owner_scroll_layer->scroll_container_bounds().width());
-      scroll_delta = viewport_length * kMinFractionToStepWhenPaging;
+      scroll_delta =
+          GetViewportLength(scrollbar) * kMinFractionToStepWhenPaging;
       break;
+    }
     default:
       scroll_delta = 0;
   }

cc/input/scrollbar_controller.h

@@ -247,6 +247,9 @@ class CC_EXPORT ScrollbarController {
   // Returns the ratio of the scroller length to the scrollbar length. This is
   // needed to scale the scroll delta for thumb drag.
   float GetScrollerToScrollbarRatio(const ScrollbarLayerImplBase* scrollbar);
+
+  int GetViewportLength(const ScrollbarLayerImplBase* scrollbar) const;
+
   LayerTreeHostImpl* layer_tree_host_impl_;
 
   // Used to safeguard against firing GSE without firing GSB and GSU. For

cc/input/single_scrollbar_animation_controller_thinning_unittest.cc

@@ -62,7 +62,6 @@ class SingleScrollbarAnimationControllerThinningTest
     root_layer()->SetBounds(gfx::Size(100, 100));
     auto* scroll_layer = AddLayer<LayerImpl>();
     scroll_layer->SetBounds(gfx::Size(200, 200));
-    scroll_layer->SetScrollable(gfx::Size(100, 100));
     scroll_layer->SetElementId(
         LayerIdToElementIdForTesting(scroll_layer->id()));
 
@@ -79,7 +78,7 @@ class SingleScrollbarAnimationControllerThinningTest
 
     CopyProperties(root_layer(), scroll_layer);
     CreateTransformNode(scroll_layer);
-    CreateScrollNode(scroll_layer);
+    CreateScrollNode(scroll_layer, gfx::Size(100, 100));
     CopyProperties(scroll_layer, scrollbar_layer_);
     scrollbar_layer_->SetOffsetToTransformParent(gfx::Vector2dF(90, 0));
     CreateEffectNode(scrollbar_layer_).has_potential_opacity_animation = true;