Determine MaxScrollOffset without using 'tree' structure of LayerTree

* Use IsAffectedByPageScale instead of the tree structure to determine the scale factor in MaxScrollOffset();
* Fix related unit tests
* Fix a variable name issue of the previous changelist (Issue 1544103002)

BUG=568777
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review URL: https://codereview.chromium.org/1552803002

Cr-Commit-Position: refs/heads/master@{#368087}

9 files changed, 103 insertions, 66 deletions

diff --git a/cc/layers/heads_up_display_layer_impl_unittest.cc b/cc/layers/heads_up_display_layer_impl_unittest.cc
index 1535787..cb69b1b 100644
--- a/cc/layers/heads_up_display_layer_impl_unittest.cc
+++ b/cc/layers/heads_up_display_layer_impl_unittest.cc
@@ -43,23 +43,23 @@ TEST(HeadsUpDisplayLayerImplTest, ResourcelessSoftwareDrawAfterResourceLoss) {
   host_impl.CreatePendingTree();
   host_impl.SetVisible(true);
   host_impl.InitializeRenderer(output_surface.get());
-  scoped_ptr<HeadsUpDisplayLayerImpl> layer =
-    HeadsUpDisplayLayerImpl::Create(host_impl.pending_tree(), 1);
-  layer->SetBounds(gfx::Size(100, 100));
+  scoped_ptr<HeadsUpDisplayLayerImpl> layer_ptr =
+      HeadsUpDisplayLayerImpl::Create(host_impl.pending_tree(), 1);
+  layer_ptr->SetBounds(gfx::Size(100, 100));
 
-  HeadsUpDisplayLayerImpl* layer_ptr = layer.get();
+  HeadsUpDisplayLayerImpl* layer = layer_ptr.get();
 
-  host_impl.pending_tree()->SetRootLayer(std::move(layer));
+  host_impl.pending_tree()->SetRootLayer(std::move(layer_ptr));
   host_impl.pending_tree()->BuildPropertyTreesForTesting();
 
   // Check regular hardware draw is ok.
-  CheckDrawLayer(layer_ptr, host_impl.resource_provider(), DRAW_MODE_HARDWARE);
+  CheckDrawLayer(layer, host_impl.resource_provider(), DRAW_MODE_HARDWARE);
 
   // Simulate a resource loss on transitioning to resourceless software mode.
-  layer_ptr->ReleaseResources();
+  layer->ReleaseResources();
 
   // Should skip resourceless software draw and not crash in UpdateHudTexture.
-  CheckDrawLayer(layer_ptr, host_impl.resource_provider(),
+  CheckDrawLayer(layer, host_impl.resource_provider(),
                  DRAW_MODE_RESOURCELESS_SOFTWARE);
 }
 
diff --git a/cc/layers/layer_impl.cc b/cc/layers/layer_impl.cc
index b590f71..f36215d 100644
--- a/cc/layers/layer_impl.cc
+++ b/cc/layers/layer_impl.cc
@@ -1600,12 +1600,9 @@ gfx::ScrollOffset LayerImpl::MaxScrollOffset() const {
          IsContainerForFixedPositionLayers());
 
   float scale_factor = 1.f;
-  for (LayerImpl const* current_layer = this;
-       current_layer != scroll_clip_layer->parent();
-       current_layer = current_layer->parent()) {
-    if (current_layer == page_scale_layer)
-      scale_factor = layer_tree_impl()->current_page_scale_factor();
-  }
+  DCHECK(scroll_clip_layer != page_scale_layer);
+  if (!scroll_clip_layer->IsAffectedByPageScale() && IsAffectedByPageScale())
+    scale_factor = layer_tree_impl()->current_page_scale_factor();
 
   gfx::SizeF scaled_scroll_bounds =
       gfx::ScaleSize(BoundsForScrolling(), scale_factor);
diff --git a/cc/layers/layer_impl_unittest.cc b/cc/layers/layer_impl_unittest.cc
index 7666794..b9fb767 100644
--- a/cc/layers/layer_impl_unittest.cc
+++ b/cc/layers/layer_impl_unittest.cc
@@ -100,12 +100,13 @@ TEST(LayerImplTest, VerifyLayerChangesAreTrackedProperly) {
                                   &task_graph_runner);
   host_impl.SetVisible(true);
   EXPECT_TRUE(host_impl.InitializeRenderer(output_surface.get()));
-  scoped_ptr<LayerImpl> root_clip =
+  scoped_ptr<LayerImpl> root_clip_ptr =
       LayerImpl::Create(host_impl.active_tree(), 1);
+  LayerImpl* root_clip = root_clip_ptr.get();
   scoped_ptr<LayerImpl> root_ptr =
       LayerImpl::Create(host_impl.active_tree(), 2);
   LayerImpl* root = root_ptr.get();
-  root_clip->AddChild(std::move(root_ptr));
+  root_clip_ptr->AddChild(std::move(root_ptr));
   scoped_ptr<LayerImpl> scroll_parent =
       LayerImpl::Create(host_impl.active_tree(), 3);
   LayerImpl* scroll_child = LayerImpl::Create(host_impl.active_tree(), 4).get();
@@ -125,6 +126,8 @@ TEST(LayerImplTest, VerifyLayerChangesAreTrackedProperly) {
   LayerImpl* child = root->children()[0].get();
   child->AddChild(LayerImpl::Create(host_impl.active_tree(), 8));
   LayerImpl* grand_child = child->children()[0].get();
+  host_impl.active_tree()->SetRootLayer(std::move(root_clip_ptr));
+  host_impl.active_tree()->BuildPropertyTreesForTesting();
 
   root->SetScrollClipLayer(root_clip->id());
 
@@ -464,6 +467,7 @@ class LayerImplScrollTest : public testing::Test {
         LayerImpl::Create(host_impl_.active_tree(), root_id_));
     host_impl_.active_tree()->root_layer()->AddChild(
         LayerImpl::Create(host_impl_.active_tree(), root_id_ + 1));
+    host_impl_.active_tree()->BuildPropertyTreesForTesting();
     layer()->SetScrollClipLayer(root_id_);
     // Set the max scroll offset by noting that the root layer has bounds (1,1),
     // thus whatever bounds are set for the layer will be the max scroll
diff --git a/cc/layers/scrollbar_layer_unittest.cc b/cc/layers/scrollbar_layer_unittest.cc
index 0202f4b4..b9fc9ae 100644
--- a/cc/layers/scrollbar_layer_unittest.cc
+++ b/cc/layers/scrollbar_layer_unittest.cc
@@ -223,6 +223,7 @@ TEST_F(ScrollbarLayerTest, ScrollOffsetSynchronization) {
   content_layer->SetBounds(gfx::Size(1000, 2000));
   content_layer->SavePaintProperties();
 
+  layer_tree_host_->UpdateLayers();
   layer_impl_tree_root = layer_tree_host_->CommitAndCreateLayerImplTree();
 
   EXPECT_EQ(100.f, cc_scrollbar_layer->current_pos());
@@ -448,6 +449,7 @@ TEST_F(ScrollbarLayerTest, LayerDrivenSolidColorDrawQuads) {
     scroll_layer->InsertChild(child2, 1);
     layer_tree_root->AddChild(scroll_layer);
     layer_tree_host_->SetRootLayer(layer_tree_root);
+    layer_tree_host_->UpdateLayers();
   }
   LayerImpl* layer_impl_tree_root =
       layer_tree_host_->CommitAndCreateLayerImplTree();
diff --git a/cc/test/layer_tree_test.cc b/cc/test/layer_tree_test.cc
index 3234d45..06822e3 100644
--- a/cc/test/layer_tree_test.cc
+++ b/cc/test/layer_tree_test.cc
@@ -70,8 +70,7 @@ void CreateVirtualViewportLayers(Layer* root_layer,
 
     inner_viewport_scroll_layer->SetIsContainerForFixedPositionLayers(true);
     outer_scroll_layer->SetIsContainerForFixedPositionLayers(true);
-    host->RegisterViewportLayers(NULL,
-                                 root_layer,
+    host->RegisterViewportLayers(NULL, page_scale_layer,
                                  inner_viewport_scroll_layer,
                                  outer_scroll_layer);
 }
diff --git a/cc/trees/layer_tree_host_impl_unittest.cc b/cc/trees/layer_tree_host_impl_unittest.cc
index 2fc38a0..1d422e8 100644
--- a/cc/trees/layer_tree_host_impl_unittest.cc
+++ b/cc/trees/layer_tree_host_impl_unittest.cc
@@ -368,6 +368,7 @@ class LayerTreeHostImplTest : public testing::Test,
         host_impl_->InnerViewportScrollLayer()->parent()->parent();
     inner_clip_layer->SetBounds(viewport_size);
     host_impl_->InnerViewportScrollLayer()->SetBounds(viewport_size);
+    host_impl_->active_tree()->BuildPropertyTreesForTesting();
 
     host_impl_->SetViewportSize(viewport_size);
     host_impl_->active_tree()->DidBecomeActive();
@@ -571,9 +572,11 @@ TEST_F(LayerTreeHostImplTest, ScrollDeltaRepeatedScrolls) {
     root_layer->SetBounds(gfx::Size(110, 110));
     root_layer->SetScrollClipLayer(root_clip->id());
     root_layer->PushScrollOffsetFromMainThread(scroll_offset);
-    root_layer->ScrollBy(scroll_delta);
     host_impl_->active_tree()->SetRootLayer(std::move(root_clip));
+    host_impl_->active_tree()->BuildPropertyTreesForTesting();
+    root_layer->ScrollBy(scroll_delta);
   }
+
   LayerImpl* root =
       host_impl_->active_tree()->root_layer()->children()[0].get();
 
@@ -1088,7 +1091,7 @@ TEST_F(LayerTreeHostImplTest, ScrollWithUserUnscrollableLayers) {
   ASSERT_EQ(1u, scroll_layer->children().size());
   LayerImpl* overflow = scroll_layer->children()[0].get();
   overflow->SetBounds(overflow_size);
-  overflow->SetScrollClipLayer(scroll_layer->parent()->id());
+  overflow->SetScrollClipLayer(scroll_layer->parent()->parent()->id());
   overflow->PushScrollOffsetFromMainThread(gfx::ScrollOffset());
   overflow->SetPosition(gfx::PointF());
 
@@ -2224,6 +2227,7 @@ TEST_F(LayerTreeHostImplTest, PageScaleAnimationTransferedOnSyncTreeActivate) {
   CreateScrollAndContentsLayers(
       host_impl_->pending_tree(),
       gfx::Size(100, 100));
+  host_impl_->pending_tree()->BuildPropertyTreesForTesting();
   host_impl_->ActivateSyncTree();
   DrawFrame();
 
@@ -3547,6 +3551,7 @@ TEST_F(LayerTreeHostImplTest, ClampingAfterActivation) {
   host_impl_->pending_tree()->PushPageScaleFromMainThread(1.f, 1.f, 1.f);
   CreateScrollAndContentsLayers(host_impl_->pending_tree(),
                                 gfx::Size(100, 100));
+  host_impl_->pending_tree()->BuildPropertyTreesForTesting();
   host_impl_->ActivateSyncTree();
 
   host_impl_->CreatePendingTree();
@@ -3635,6 +3640,7 @@ class LayerTreeHostImplTopControlsTest : public LayerTreeHostImplTest {
     host_impl_->active_tree()->SetViewportLayersFromIds(
         Layer::INVALID_ID, page_scale_layer_id, inner_viewport_scroll_layer_id,
         outer_viewport_scroll_layer_id);
+    host_impl_->active_tree()->BuildPropertyTreesForTesting();
 
     host_impl_->SetViewportSize(inner_viewport_size);
     LayerImpl* root_clip_ptr = host_impl_->active_tree()->root_layer();
@@ -4634,26 +4640,30 @@ TEST_F(LayerTreeHostImplTest, ScrollWithoutBubbling) {
   // the scroll doesn't bubble up to the parent layer.
   gfx::Size surface_size(20, 20);
   gfx::Size viewport_size(10, 10);
-  scoped_ptr<LayerImpl> root = LayerImpl::Create(host_impl_->active_tree(), 1);
-  root->SetForceRenderSurface(true);
+  scoped_ptr<LayerImpl> root_ptr =
+      LayerImpl::Create(host_impl_->active_tree(), 1);
+  scoped_ptr<LayerImpl> root_clip =
+      LayerImpl::Create(host_impl_->active_tree(), 2);
+  root_clip->SetForceRenderSurface(true);
   scoped_ptr<LayerImpl> root_scrolling =
-      CreateScrollableLayer(2, surface_size, root.get());
+      CreateScrollableLayer(3, surface_size, root_clip.get());
   root_scrolling->SetIsContainerForFixedPositionLayers(true);
 
   scoped_ptr<LayerImpl> grand_child =
-      CreateScrollableLayer(4, surface_size, root.get());
+      CreateScrollableLayer(5, surface_size, root_clip.get());
 
   scoped_ptr<LayerImpl> child =
-      CreateScrollableLayer(3, surface_size, root.get());
+      CreateScrollableLayer(4, surface_size, root_clip.get());
   LayerImpl* grand_child_layer = grand_child.get();
   child->AddChild(std::move(grand_child));
 
   LayerImpl* child_layer = child.get();
   root_scrolling->AddChild(std::move(child));
-  root->AddChild(std::move(root_scrolling));
-  EXPECT_EQ(viewport_size, root->bounds());
-  host_impl_->active_tree()->SetRootLayer(std::move(root));
-  host_impl_->active_tree()->SetViewportLayersFromIds(Layer::INVALID_ID, 1, 2,
+  root_clip->AddChild(std::move(root_scrolling));
+  EXPECT_EQ(viewport_size, root_clip->bounds());
+  root_ptr->AddChild(std::move(root_clip));
+  host_impl_->active_tree()->SetRootLayer(std::move(root_ptr));
+  host_impl_->active_tree()->SetViewportLayersFromIds(Layer::INVALID_ID, 1, 3,
                                                       Layer::INVALID_ID);
   host_impl_->active_tree()->DidBecomeActive();
   host_impl_->SetViewportSize(viewport_size);
@@ -4674,9 +4684,12 @@ TEST_F(LayerTreeHostImplTest, ScrollWithoutBubbling) {
         host_impl_->ProcessScrollDeltas();
 
     // The grand child should have scrolled up to its limit.
-    LayerImpl* child =
-        host_impl_->active_tree()->root_layer()->children()[0]->children()
-            [0].get();
+    LayerImpl* child = host_impl_->active_tree()
+                           ->root_layer()
+                           ->children()[0]
+                           ->children()[0]
+                           ->children()[0]
+                           .get();
     LayerImpl* grand_child = child->children()[0].get();
     EXPECT_TRUE(ScrollInfoContains(*scroll_info.get(), grand_child->id(),
                                    gfx::Vector2d(0, -2)));
@@ -4749,25 +4762,28 @@ TEST_F(LayerTreeHostImplTest, ScrollEventBubbling) {
   // should be applied to one of its ancestors if possible.
   gfx::Size surface_size(10, 10);
   gfx::Size content_size(20, 20);
+  scoped_ptr<LayerImpl> root_ptr =
+      LayerImpl::Create(host_impl_->active_tree(), 4);
   scoped_ptr<LayerImpl> root_clip =
       LayerImpl::Create(host_impl_->active_tree(), 3);
   root_clip->SetForceRenderSurface(true);
-  scoped_ptr<LayerImpl> root =
+  scoped_ptr<LayerImpl> root_scroll =
       CreateScrollableLayer(1, content_size, root_clip.get());
   // Make 'root' the clip layer for child: since they have the same sizes the
   // child will have zero max_scroll_offset and scrolls will bubble.
   scoped_ptr<LayerImpl> child =
-      CreateScrollableLayer(2, content_size, root.get());
+      CreateScrollableLayer(2, content_size, root_scroll.get());
   child->SetIsContainerForFixedPositionLayers(true);
-  root->SetBounds(content_size);
+  root_scroll->SetBounds(content_size);
 
-  int root_scroll_id = root->id();
-  root->AddChild(std::move(child));
-  root_clip->AddChild(std::move(root));
+  int root_scroll_id = root_scroll->id();
+  root_scroll->AddChild(std::move(child));
+  root_clip->AddChild(std::move(root_scroll));
+  root_ptr->AddChild(std::move(root_clip));
 
   host_impl_->SetViewportSize(surface_size);
-  host_impl_->active_tree()->SetRootLayer(std::move(root_clip));
-  host_impl_->active_tree()->SetViewportLayersFromIds(Layer::INVALID_ID, 3, 2,
+  host_impl_->active_tree()->SetRootLayer(std::move(root_ptr));
+  host_impl_->active_tree()->SetViewportLayersFromIds(Layer::INVALID_ID, 4, 2,
                                                       Layer::INVALID_ID);
   host_impl_->active_tree()->DidBecomeActive();
   DrawFrame();
@@ -4790,15 +4806,18 @@ TEST_F(LayerTreeHostImplTest, ScrollEventBubbling) {
 
 TEST_F(LayerTreeHostImplTest, ScrollBeforeRedraw) {
   gfx::Size surface_size(10, 10);
-  scoped_ptr<LayerImpl> root_clip =
+  scoped_ptr<LayerImpl> root_ptr =
       LayerImpl::Create(host_impl_->active_tree(), 1);
+  scoped_ptr<LayerImpl> root_clip =
+      LayerImpl::Create(host_impl_->active_tree(), 2);
   scoped_ptr<LayerImpl> root_scroll =
-      CreateScrollableLayer(2, surface_size, root_clip.get());
+      CreateScrollableLayer(3, surface_size, root_clip.get());
   root_scroll->SetIsContainerForFixedPositionLayers(true);
   root_clip->SetForceRenderSurface(true);
   root_clip->AddChild(std::move(root_scroll));
-  host_impl_->active_tree()->SetRootLayer(std::move(root_clip));
-  host_impl_->active_tree()->SetViewportLayersFromIds(Layer::INVALID_ID, 1, 2,
+  root_ptr->AddChild(std::move(root_clip));
+  host_impl_->active_tree()->SetRootLayer(std::move(root_ptr));
+  host_impl_->active_tree()->SetViewportLayersFromIds(Layer::INVALID_ID, 1, 3,
                                                       Layer::INVALID_ID);
   host_impl_->active_tree()->DidBecomeActive();
   host_impl_->SetViewportSize(surface_size);
@@ -4807,15 +4826,18 @@ TEST_F(LayerTreeHostImplTest, ScrollBeforeRedraw) {
   // synchronization.
   DrawFrame();
   host_impl_->active_tree()->DetachLayerTree();
+  scoped_ptr<LayerImpl> root_ptr2 =
+      LayerImpl::Create(host_impl_->active_tree(), 4);
   scoped_ptr<LayerImpl> root_clip2 =
-      LayerImpl::Create(host_impl_->active_tree(), 3);
+      LayerImpl::Create(host_impl_->active_tree(), 5);
   scoped_ptr<LayerImpl> root_scroll2 =
-      CreateScrollableLayer(4, surface_size, root_clip2.get());
+      CreateScrollableLayer(6, surface_size, root_clip2.get());
   root_scroll2->SetIsContainerForFixedPositionLayers(true);
   root_clip2->AddChild(std::move(root_scroll2));
   root_clip2->SetForceRenderSurface(true);
-  host_impl_->active_tree()->SetRootLayer(std::move(root_clip2));
-  host_impl_->active_tree()->SetViewportLayersFromIds(Layer::INVALID_ID, 3, 4,
+  root_ptr2->AddChild(std::move(root_clip2));
+  host_impl_->active_tree()->SetRootLayer(std::move(root_ptr2));
+  host_impl_->active_tree()->SetViewportLayersFromIds(Layer::INVALID_ID, 4, 6,
                                                       Layer::INVALID_ID);
   host_impl_->active_tree()->DidBecomeActive();
 
@@ -5220,6 +5242,7 @@ TEST_F(LayerTreeHostImplTest, RootLayerScrollOffsetDelegation) {
   host_impl_->CreatePendingTree();
   host_impl_->pending_tree()->PushPageScaleFromMainThread(1.f, 1.f, 1.f);
   CreateScrollAndContentsLayers(host_impl_->pending_tree(), new_size);
+  host_impl_->pending_tree()->BuildPropertyTreesForTesting();
   host_impl_->ActivateSyncTree();
   EXPECT_EQ(gfx::SizeF(new_size), scroll_watcher.scrollable_size());
 
@@ -7213,23 +7236,26 @@ TEST_F(LayerTreeHostImplTest, TouchFlingShouldNotBubble) {
   // bubble).
   gfx::Size surface_size(10, 10);
   gfx::Size content_size(20, 20);
+  scoped_ptr<LayerImpl> root_ptr =
+      LayerImpl::Create(host_impl_->active_tree(), 4);
   scoped_ptr<LayerImpl> root_clip =
       LayerImpl::Create(host_impl_->active_tree(), 3);
   root_clip->SetForceRenderSurface(true);
 
-  scoped_ptr<LayerImpl> root =
+  scoped_ptr<LayerImpl> root_scroll =
       CreateScrollableLayer(1, content_size, root_clip.get());
-  root->SetIsContainerForFixedPositionLayers(true);
+  root_scroll->SetIsContainerForFixedPositionLayers(true);
   scoped_ptr<LayerImpl> child =
       CreateScrollableLayer(2, content_size, root_clip.get());
 
-  root->AddChild(std::move(child));
-  int root_id = root->id();
-  root_clip->AddChild(std::move(root));
+  root_scroll->AddChild(std::move(child));
+  int root_id = root_scroll->id();
+  root_clip->AddChild(std::move(root_scroll));
+  root_ptr->AddChild(std::move(root_clip));
 
   host_impl_->SetViewportSize(surface_size);
-  host_impl_->active_tree()->SetRootLayer(std::move(root_clip));
-  host_impl_->active_tree()->SetViewportLayersFromIds(Layer::INVALID_ID, 3, 1,
+  host_impl_->active_tree()->SetRootLayer(std::move(root_ptr));
+  host_impl_->active_tree()->SetViewportLayersFromIds(Layer::INVALID_ID, 4, 1,
                                                       Layer::INVALID_ID);
   host_impl_->active_tree()->DidBecomeActive();
   DrawFrame();
diff --git a/cc/trees/layer_tree_host_unittest.cc b/cc/trees/layer_tree_host_unittest.cc
index 6974c92..4a4246a 100644
--- a/cc/trees/layer_tree_host_unittest.cc
+++ b/cc/trees/layer_tree_host_unittest.cc
@@ -5188,12 +5188,15 @@ class LayerTreeHostTestCrispUpAfterPinchEnds : public LayerTreeHostTest {
 
     scoped_refptr<Layer> root = Layer::Create(layer_settings());
     root->SetBounds(gfx::Size(500, 500));
+    scoped_refptr<Layer> clip = Layer::Create(layer_settings());
+    clip->SetBounds(gfx::Size(500, 500));
 
     scoped_refptr<Layer> pinch = Layer::Create(layer_settings());
     pinch->SetBounds(gfx::Size(500, 500));
-    pinch->SetScrollClipLayerId(root->id());
+    pinch->SetScrollClipLayerId(clip->id());
     pinch->SetIsContainerForFixedPositionLayers(true);
-    root->AddChild(pinch);
+    clip->AddChild(pinch);
+    root->AddChild(clip);
 
     scoped_ptr<FakeDisplayListRecordingSource> recording(
         new FakeDisplayListRecordingSource);
@@ -5489,12 +5492,15 @@ class LayerTreeHostTestContinuousDrawWhenCreatingVisibleTiles
 
     scoped_refptr<Layer> root = Layer::Create(layer_settings());
     root->SetBounds(gfx::Size(500, 500));
+    scoped_refptr<Layer> clip = Layer::Create(layer_settings());
+    clip->SetBounds(gfx::Size(500, 500));
 
     scoped_refptr<Layer> pinch = Layer::Create(layer_settings());
     pinch->SetBounds(gfx::Size(500, 500));
-    pinch->SetScrollClipLayerId(root->id());
+    pinch->SetScrollClipLayerId(clip->id());
     pinch->SetIsContainerForFixedPositionLayers(true);
-    root->AddChild(pinch);
+    clip->AddChild(pinch);
+    root->AddChild(clip);
 
     scoped_ptr<FakeDisplayListRecordingSource> recording(
         new FakeDisplayListRecordingSource);
@@ -5512,7 +5518,7 @@ class LayerTreeHostTestContinuousDrawWhenCreatingVisibleTiles
     layer_tree_host()->SetPageScaleFactorAndLimits(1.f, 1.f, 4.f);
     layer_tree_host()->SetRootLayer(root);
     LayerTreeHostTest::SetupTree();
-    client_.set_bounds(root->bounds());
+    client_.set_bounds(clip->bounds());
   }
 
   // Returns the delta scale of all quads in the frame's root pass from their
diff --git a/cc/trees/layer_tree_host_unittest_picture.cc b/cc/trees/layer_tree_host_unittest_picture.cc
index 8dec586..4a1a641 100644
--- a/cc/trees/layer_tree_host_unittest_picture.cc
+++ b/cc/trees/layer_tree_host_unittest_picture.cc
@@ -402,12 +402,15 @@ class LayerTreeHostPictureTestRSLLMembershipWithScale
   void SetupTree() override {
     scoped_refptr<Layer> root = Layer::Create(layer_settings());
     root->SetBounds(gfx::Size(100, 100));
+    scoped_refptr<Layer> clip = Layer::Create(layer_settings());
+    clip->SetBounds(gfx::Size(100, 100));
 
     pinch_ = Layer::Create(layer_settings());
     pinch_->SetBounds(gfx::Size(500, 500));
-    pinch_->SetScrollClipLayerId(root->id());
+    pinch_->SetScrollClipLayerId(clip->id());
     pinch_->SetIsContainerForFixedPositionLayers(true);
-    root->AddChild(pinch_);
+    clip->AddChild(pinch_);
+    root->AddChild(clip);
 
     // Don't be solid color so the layer has tilings/tiles.
     client_.set_fill_with_nonsolid_color(true);
@@ -436,7 +439,7 @@ class LayerTreeHostPictureTestRSLLMembershipWithScale
 
   void WillActivateTreeOnThread(LayerTreeHostImpl* impl) override {
     LayerImpl* root = impl->sync_tree()->root_layer();
-    LayerImpl* pinch = root->children()[0].get();
+    LayerImpl* pinch = root->children()[0]->children()[0].get();
     LayerImpl* gchild = pinch->children()[0].get();
     FakePictureLayerImpl* picture = static_cast<FakePictureLayerImpl*>(gchild);
     ready_to_draw_ = false;
@@ -463,7 +466,7 @@ class LayerTreeHostPictureTestRSLLMembershipWithScale
 
   void DrawLayersOnThread(LayerTreeHostImpl* impl) override {
     LayerImpl* root = impl->active_tree()->root_layer();
-    LayerImpl* pinch = root->children()[0].get();
+    LayerImpl* pinch = root->children()[0]->children()[0].get();
     LayerImpl* gchild = pinch->children()[0].get();
     FakePictureLayerImpl* picture = static_cast<FakePictureLayerImpl*>(gchild);
 
diff --git a/cc/trees/layer_tree_host_unittest_scroll.cc b/cc/trees/layer_tree_host_unittest_scroll.cc
index d7f8c32..380a0c2 100644
--- a/cc/trees/layer_tree_host_unittest_scroll.cc
+++ b/cc/trees/layer_tree_host_unittest_scroll.cc
@@ -80,7 +80,7 @@ class LayerTreeHostScrollTestScrollSimple : public LayerTreeHostScrollTest {
     LayerImpl* scroll_layer = impl->OuterViewportScrollLayer();
     EXPECT_VECTOR_EQ(gfx::Vector2d(), scroll_layer->ScrollDelta());
 
-    scroll_layer->SetScrollClipLayer(root->id());
+    scroll_layer->SetScrollClipLayer(root->children()[0]->id());
     scroll_layer->SetBounds(
         gfx::Size(root->bounds().width() + 100, root->bounds().height() + 100));
     scroll_layer->ScrollBy(scroll_amount_);
@@ -1011,7 +1011,7 @@ class LayerTreeHostScrollTestScrollZeroMaxScrollOffset
   void DrawLayersOnThread(LayerTreeHostImpl* impl) override {
     LayerImpl* root = impl->active_tree()->root_layer();
     LayerImpl* scroll_layer = impl->OuterViewportScrollLayer();
-    scroll_layer->SetScrollClipLayer(root->id());
+    scroll_layer->SetScrollClipLayer(root->children()[0]->id());
 
     // Set max_scroll_offset = (100, 100).
     scroll_layer->SetBounds(