Revert of Pinch/Zoom Infrastructure & Plumbing CL

cc/trees/layer_tree_impl.cc

Index: cc/trees/layer_tree_impl.cc
diff --git a/cc/trees/layer_tree_impl.cc b/cc/trees/layer_tree_impl.cc
index e7b24c7fd844fd2739732067b48e9d2302a1762e..34130dec4e504627c58de92e637c0fc980072b7a 100644
--- a/cc/trees/layer_tree_impl.cc
+++ b/cc/trees/layer_tree_impl.cc
@@ -22,62 +22,11 @@
 
 namespace cc {
 
-// This class exists to split the LayerScrollOffsetDelegate between the
-// InnerViewportScrollLayer and the OuterViewportScrollLayer in a manner
-// that never requires the embedder or LayerImpl to know about.
-class LayerScrollOffsetDelegateProxy : public LayerScrollOffsetDelegate {
- public:
-  LayerScrollOffsetDelegateProxy(LayerImpl* layer,
-                                 LayerScrollOffsetDelegate* delegate,
-                                 LayerTreeImpl* layer_tree)
-      : layer_(layer),
-        delegate_(delegate),
-        layer_tree_impl_(layer_tree) {}
-
-  gfx::Vector2dF last_set_scroll_offset() const {
-    return last_set_scroll_offset_;
-  }
-
-  // LayerScrollOffsetDelegate implementation.
-
-  virtual void SetTotalScrollOffset(const gfx::Vector2dF& new_offset) OVERRIDE {
-    last_set_scroll_offset_ = new_offset;
-    layer_tree_impl_->UpdateScrollOffsetDelegate();
-  }
-
-  virtual gfx::Vector2dF GetTotalScrollOffset() OVERRIDE {
-    return layer_tree_impl_->GetDelegatedScrollOffset(layer_);
-  }
-
-  virtual bool IsExternalFlingActive() const OVERRIDE {
-    return delegate_->IsExternalFlingActive();
-  }
-
-  // Functions below this point are never called by LayerImpl on its
-  // LayerScrollOffsetDelegate, and so are not implemented.
-  virtual void SetMaxScrollOffset(const gfx::Vector2dF&) OVERRIDE {
-    NOTIMPLEMENTED();
-  }
-
-  virtual void SetTotalPageScaleFactor(float scale) OVERRIDE {
-    NOTIMPLEMENTED();
-  }
-
-  virtual void SetScrollableSize(const gfx::SizeF& scrollable_size) OVERRIDE {
-    NOTIMPLEMENTED();
-  }
-
- private:
-  LayerImpl* layer_;
-  LayerScrollOffsetDelegate* delegate_;
-  LayerTreeImpl* layer_tree_impl_;
-  gfx::Vector2dF last_set_scroll_offset_;
-};
-
 LayerTreeImpl::LayerTreeImpl(LayerTreeHostImpl* layer_tree_host_impl)
     : layer_tree_host_impl_(layer_tree_host_impl),
       source_frame_number_(-1),
       hud_layer_(0),
+      root_scroll_layer_(NULL),
       currently_scrolling_layer_(NULL),
       root_layer_scroll_offset_delegate_(NULL),
       background_color_(0),
@@ -104,77 +53,57 @@
   root_layer_.reset();
 }
 
+static LayerImpl* FindRootScrollLayerRecursive(LayerImpl* layer) {
+  if (!layer)
+    return NULL;
+
+  if (layer->scrollable())
+    return layer;
+
+  for (size_t i = 0; i < layer->children().size(); ++i) {
+    LayerImpl* found = FindRootScrollLayerRecursive(layer->children()[i]);
+    if (found)
+      return found;
+  }
+
+  return NULL;
+}
+
 void LayerTreeImpl::SetRootLayer(scoped_ptr<LayerImpl> layer) {
-  if (inner_viewport_scroll_layer_)
-    inner_viewport_scroll_layer_->SetScrollOffsetDelegate(NULL);
-  if (outer_viewport_scroll_layer_)
-    outer_viewport_scroll_layer_->SetScrollOffsetDelegate(NULL);
-  inner_viewport_scroll_delegate_proxy_.reset();
-  outer_viewport_scroll_delegate_proxy_.reset();
-
+  if (root_scroll_layer_)
+    root_scroll_layer_->SetScrollOffsetDelegate(NULL);
   root_layer_ = layer.Pass();
   currently_scrolling_layer_ = NULL;
-  inner_viewport_scroll_layer_ = NULL;
-  outer_viewport_scroll_layer_ = NULL;
-  page_scale_layer_ = NULL;
+  root_scroll_layer_ = NULL;
 
   layer_tree_host_impl_->OnCanDrawStateChangedForTree();
 }
 
-LayerImpl* LayerTreeImpl::InnerViewportScrollLayer() const {
-  return inner_viewport_scroll_layer_;
-}
-
-LayerImpl* LayerTreeImpl::OuterViewportScrollLayer() const {
-  return outer_viewport_scroll_layer_;
-}
-
-gfx::Vector2dF LayerTreeImpl::TotalScrollOffset() const {
-  gfx::Vector2dF offset;
-
-  if (inner_viewport_scroll_layer_)
-    offset += inner_viewport_scroll_layer_->TotalScrollOffset();
-
-  if (outer_viewport_scroll_layer_)
-    offset += outer_viewport_scroll_layer_->TotalScrollOffset();
-
-  return offset;
-}
-
-gfx::Vector2dF LayerTreeImpl::TotalMaxScrollOffset() const {
-  gfx::Vector2dF offset;
-
-  if (inner_viewport_scroll_layer_)
-    offset += inner_viewport_scroll_layer_->MaxScrollOffset();
-
-  if (outer_viewport_scroll_layer_)
-    offset += outer_viewport_scroll_layer_->MaxScrollOffset();
-
-  return offset;
-}
-gfx::Vector2dF LayerTreeImpl::TotalScrollDelta() const {
-  DCHECK(inner_viewport_scroll_layer_);
-  gfx::Vector2dF delta = inner_viewport_scroll_layer_->ScrollDelta();
-
-  if (outer_viewport_scroll_layer_)
-    delta += outer_viewport_scroll_layer_->ScrollDelta();
-
-  return delta;
+void LayerTreeImpl::FindRootScrollLayer() {
+  root_scroll_layer_ = FindRootScrollLayerRecursive(root_layer_.get());
+
+  if (root_scroll_layer_) {
+    UpdateMaxScrollOffset();
+    root_scroll_layer_->SetScrollOffsetDelegate(
+        root_layer_scroll_offset_delegate_);
+  }
+
+  if (scrolling_layer_id_from_previous_tree_) {
+    currently_scrolling_layer_ = LayerTreeHostCommon::FindLayerInSubtree(
+        root_layer_.get(),
+        scrolling_layer_id_from_previous_tree_);
+  }
+
+  scrolling_layer_id_from_previous_tree_ = 0;
 }
 
 scoped_ptr<LayerImpl> LayerTreeImpl::DetachLayerTree() {
   // Clear all data structures that have direct references to the layer tree.
   scrolling_layer_id_from_previous_tree_ =
     currently_scrolling_layer_ ? currently_scrolling_layer_->id() : 0;
-  if (inner_viewport_scroll_layer_)
-    inner_viewport_scroll_layer_->SetScrollOffsetDelegate(NULL);
-  if (outer_viewport_scroll_layer_)
-    outer_viewport_scroll_layer_->SetScrollOffsetDelegate(NULL);
-  inner_viewport_scroll_delegate_proxy_.reset();
-  outer_viewport_scroll_delegate_proxy_.reset();
-  inner_viewport_scroll_layer_ = NULL;
-  outer_viewport_scroll_layer_ = NULL;
-  page_scale_layer_ = NULL;
+  if (root_scroll_layer_)
+    root_scroll_layer_->SetScrollOffsetDelegate(NULL);
+  root_scroll_layer_ = NULL;
   currently_scrolling_layer_ = NULL;
 
   render_surface_layer_list_.clear();
@@ -199,14 +128,12 @@
       target_tree->page_scale_delta() / target_tree->sent_page_scale_delta());
   target_tree->set_sent_page_scale_delta(1);
 
-  if (page_scale_layer_ && inner_viewport_scroll_layer_) {
+  if (settings().use_pinch_virtual_viewport) {
     target_tree->SetViewportLayersFromIds(
         page_scale_layer_->id(),
         inner_viewport_scroll_layer_->id(),
         outer_viewport_scroll_layer_ ? outer_viewport_scroll_layer_->id()
                                      : Layer::INVALID_ID);
-  } else {
-    target_tree->ClearViewportLayers();
   }
   // This should match the property synchronization in
   // LayerTreeHost::finishCommitOnImplThread().
@@ -232,9 +159,12 @@
     target_tree->set_hud_layer(NULL);
 }
 
+LayerImpl* LayerTreeImpl::RootScrollLayer() const {
+  return root_scroll_layer_;
+}
+
 LayerImpl* LayerTreeImpl::RootContainerLayer() const {
-  return inner_viewport_scroll_layer_ ? inner_viewport_scroll_layer_->parent()
-                                      : NULL;
+  return root_scroll_layer_ ? root_scroll_layer_->parent() : NULL;
 }
 
 LayerImpl* LayerTreeImpl::CurrentlyScrollingLayer() const {
@@ -260,29 +190,6 @@
   scrolling_layer_id_from_previous_tree_ = 0;
 }
 
-float LayerTreeImpl::VerticalAdjust(const LayerImpl* layer) const {
-  DCHECK(layer);
-  if (layer->parent() != RootContainerLayer())
-    return 0.f;
-
-  return layer_tree_host_impl_->UnscaledScrollableViewportSize().height() -
-         RootContainerLayer()->bounds().height();
-}
-
-namespace {
-
-void ForceScrollbarParameterUpdateAfterScaleChange(LayerImpl* current_layer) {
-  if (!current_layer)
-    return;
-
-  while (current_layer) {
-      current_layer->ScrollbarParametersDidChange();
-      current_layer = current_layer->parent();
-  }
-}
-
-}  // namespace
-
 void LayerTreeImpl::SetPageScaleFactorAndLimits(float page_scale_factor,
     float min_page_scale_factor, float max_page_scale_factor) {
   if (!page_scale_factor)
@@ -296,8 +203,6 @@
     root_layer_scroll_offset_delegate_->SetTotalPageScaleFactor(
         total_page_scale_factor());
   }
-
-  ForceScrollbarParameterUpdateAfterScaleChange(page_scale_layer());
 }
 
 void LayerTreeImpl::SetPageScaleDelta(float delta) {
@@ -322,6 +227,7 @@
     }
   }
 
+  UpdateMaxScrollOffset();
   set_needs_update_draw_properties();
 
   if (root_layer_scroll_offset_delegate_) {
@@ -331,24 +237,32 @@
 }
 
 gfx::SizeF LayerTreeImpl::ScrollableViewportSize() const {
-  if (outer_viewport_scroll_layer_)
-    return layer_tree_host_impl_->UnscaledScrollableViewportSize();
-  else
-    return gfx::ScaleSize(
-        layer_tree_host_impl_->UnscaledScrollableViewportSize(),
-        1.0f / total_page_scale_factor());
+  return gfx::ScaleSize(layer_tree_host_impl_->UnscaledScrollableViewportSize(),
+                        1.0f / total_page_scale_factor());
 }
 
 gfx::Rect LayerTreeImpl::RootScrollLayerDeviceViewportBounds() const {
-  LayerImpl* root_scroll_layer =
-      OuterViewportScrollLayer() ? OuterViewportScrollLayer()
-                                 : InnerViewportScrollLayer();
-  if (!root_scroll_layer || root_scroll_layer->children().empty())
+  if (!root_scroll_layer_ || root_scroll_layer_->children().empty())
     return gfx::Rect();
-  LayerImpl* layer = root_scroll_layer->children()[0];
+  LayerImpl* layer = root_scroll_layer_->children()[0];
   return MathUtil::MapClippedRect(
       layer->screen_space_transform(),
       gfx::Rect(layer->content_bounds()));
+}
+
+void LayerTreeImpl::UpdateMaxScrollOffset() {
+  LayerImpl* root_scroll = RootScrollLayer();
+  if (!root_scroll || !root_scroll->children().size())
+    return;
+
+  gfx::Vector2dF max_scroll = gfx::Rect(ScrollableSize()).bottom_right() -
+      gfx::RectF(ScrollableViewportSize()).bottom_right();
+
+  // The viewport may be larger than the contents in some cases, such as
+  // having a vertical scrollbar but no horizontal overflow.
+  max_scroll.SetToMax(gfx::Vector2dF());
+
+  root_scroll_layer_->SetMaxScrollOffset(gfx::ToFlooredVector2d(max_scroll));
 }
 
 static void ApplySentScrollDeltasFromAbortedCommitTo(LayerImpl* layer) {
@@ -397,20 +311,6 @@
       LayerById(outer_viewport_scroll_layer_id);
   DCHECK(outer_viewport_scroll_layer_ ||
          outer_viewport_scroll_layer_id == Layer::INVALID_ID);
-
-  if (!root_layer_scroll_offset_delegate_)
-    return;
-
-  inner_viewport_scroll_delegate_proxy_ = make_scoped_ptr(
-      new LayerScrollOffsetDelegateProxy(inner_viewport_scroll_layer_,
-                                         root_layer_scroll_offset_delegate_,
-                                         this));
-
-  if (outer_viewport_scroll_layer_)
-    outer_viewport_scroll_delegate_proxy_ = make_scoped_ptr(
-        new LayerScrollOffsetDelegateProxy(outer_viewport_scroll_layer_,
-                                           root_layer_scroll_offset_delegate_,
-                                           this));
 }
 
 void LayerTreeImpl::ClearViewportLayers() {
@@ -419,9 +319,42 @@
   outer_viewport_scroll_layer_ = NULL;
 }
 
+// TODO(wjmaclean) This needs to go away, and be replaced with a single core
+// of login that works for both scrollbar layer types. This is already planned
+// as part of the larger pinch-zoom re-factoring viewport.
+void LayerTreeImpl::UpdateSolidColorScrollbars() {
+  LayerImpl* root_scroll = RootScrollLayer();
+  DCHECK(root_scroll);
+  DCHECK(IsActiveTree());
+
+  gfx::RectF scrollable_viewport(
+      gfx::PointAtOffsetFromOrigin(root_scroll->TotalScrollOffset()),
+      ScrollableViewportSize());
+  float vertical_adjust = 0.0f;
+  if (RootContainerLayer())
+    vertical_adjust =
+        layer_tree_host_impl_->UnscaledScrollableViewportSize().height() -
+        RootContainerLayer()->bounds().height();
+  if (ScrollbarLayerImplBase* horiz =
+          root_scroll->horizontal_scrollbar_layer()) {
+    horiz->SetVerticalAdjust(vertical_adjust);
+    horiz->SetVisibleToTotalLengthRatio(
+        scrollable_viewport.width() / ScrollableSize().width());
+  }
+  if (ScrollbarLayerImplBase* vertical =
+          root_scroll->vertical_scrollbar_layer()) {
+    vertical->SetVerticalAdjust(vertical_adjust);
+    vertical->SetVisibleToTotalLengthRatio(
+        scrollable_viewport.height() / ScrollableSize().height());
+  }
+}
+
 void LayerTreeImpl::UpdateDrawProperties() {
+  if (IsActiveTree() && RootScrollLayer() && RootContainerLayer())
+    UpdateRootScrollLayerSizeDelta();
+
   if (IsActiveTree() && RootContainerLayer())
-    UpdateRootScrollLayerSizeDelta();
+    UpdateSolidColorScrollbars();
 
   needs_update_draw_properties_ = false;
   render_surface_layer_list_.clear();
@@ -501,11 +434,9 @@
 }
 
 gfx::Size LayerTreeImpl::ScrollableSize() const {
-  LayerImpl* root_scroll_layer = OuterViewportScrollLayer() ?
-      OuterViewportScrollLayer() : InnerViewportScrollLayer();
-  if (!root_scroll_layer || root_scroll_layer->children().empty())
+  if (!root_scroll_layer_ || root_scroll_layer_->children().empty())
     return gfx::Size();
-  return root_scroll_layer->children()[0]->bounds();
+  return root_scroll_layer_->children()[0]->bounds();
 }
 
 LayerImpl* LayerTreeImpl::LayerById(int id) {
@@ -539,13 +470,8 @@
   if (!root_layer())
     return;
 
-  if (scrolling_layer_id_from_previous_tree_) {
-    currently_scrolling_layer_ = LayerTreeHostCommon::FindLayerInSubtree(
-        root_layer_.get(),
-        scrolling_layer_id_from_previous_tree_);
-  }
-
   DidBecomeActiveRecursive(root_layer());
+  FindRootScrollLayer();
 }
 
 bool LayerTreeImpl::ContentsTexturesPurged() const {
@@ -736,110 +662,22 @@
   if (root_layer_scroll_offset_delegate_ == root_layer_scroll_offset_delegate)
     return;
 
-  if (!root_layer_scroll_offset_delegate) {
-    // Make sure we remove the proxies from their layers before
-    // releasing them.
-    if (InnerViewportScrollLayer())
-      InnerViewportScrollLayer()->SetScrollOffsetDelegate(NULL);
-    if (OuterViewportScrollLayer())
-      OuterViewportScrollLayer()->SetScrollOffsetDelegate(NULL);
-    inner_viewport_scroll_delegate_proxy_.reset();
-    outer_viewport_scroll_delegate_proxy_.reset();
-  }
-
   root_layer_scroll_offset_delegate_ = root_layer_scroll_offset_delegate;
 
+  if (root_scroll_layer_) {
+    root_scroll_layer_->SetScrollOffsetDelegate(
+        root_layer_scroll_offset_delegate_);
+  }
+
   if (root_layer_scroll_offset_delegate_) {
-    root_layer_scroll_offset_delegate_->SetTotalScrollOffset(
-        TotalScrollOffset());
-    root_layer_scroll_offset_delegate_->SetMaxScrollOffset(
-        TotalMaxScrollOffset());
     root_layer_scroll_offset_delegate_->SetScrollableSize(ScrollableSize());
     root_layer_scroll_offset_delegate_->SetTotalPageScaleFactor(
         total_page_scale_factor());
-
-    if (inner_viewport_scroll_layer_) {
-      inner_viewport_scroll_delegate_proxy_ = make_scoped_ptr(
-          new LayerScrollOffsetDelegateProxy(InnerViewportScrollLayer(),
-                                             root_layer_scroll_offset_delegate_,
-                                             this));
-      inner_viewport_scroll_layer_->SetScrollOffsetDelegate(
-          inner_viewport_scroll_delegate_proxy_.get());
-    }
-
-    if (outer_viewport_scroll_layer_) {
-      outer_viewport_scroll_delegate_proxy_ = make_scoped_ptr(
-          new LayerScrollOffsetDelegateProxy(OuterViewportScrollLayer(),
-                                             root_layer_scroll_offset_delegate_,
-                                             this));
-      outer_viewport_scroll_layer_->SetScrollOffsetDelegate(
-          outer_viewport_scroll_delegate_proxy_.get());
-    }
-  }
-}
-
-void LayerTreeImpl::UpdateScrollOffsetDelegate() {
-  DCHECK(InnerViewportScrollLayer());
-  DCHECK(root_layer_scroll_offset_delegate_);
-
-  gfx::Vector2dF offset =
-      inner_viewport_scroll_delegate_proxy_->last_set_scroll_offset();
-
-  if (OuterViewportScrollLayer())
-    offset +=
-        outer_viewport_scroll_delegate_proxy_->last_set_scroll_offset();
-
-  root_layer_scroll_offset_delegate_->SetTotalScrollOffset(offset);
-  root_layer_scroll_offset_delegate_->SetMaxScrollOffset(
-      TotalMaxScrollOffset());
-}
-
-gfx::Vector2dF LayerTreeImpl::GetDelegatedScrollOffset(LayerImpl* layer) {
-  DCHECK(root_layer_scroll_offset_delegate_);
-  DCHECK(InnerViewportScrollLayer());
-  if (layer == InnerViewportScrollLayer() && !OuterViewportScrollLayer())
-    return root_layer_scroll_offset_delegate_->GetTotalScrollOffset();
-
-  // If we get here, we have both inner/outer viewports, and need to distribute
-  // the scroll offset between them.
-  DCHECK(inner_viewport_scroll_delegate_proxy_);
-  DCHECK(outer_viewport_scroll_delegate_proxy_);
-  gfx::Vector2dF inner_viewport_offset =
-      inner_viewport_scroll_delegate_proxy_->last_set_scroll_offset();
-  gfx::Vector2dF outer_viewport_offset =
-      outer_viewport_scroll_delegate_proxy_->last_set_scroll_offset();
-
-  // It may be nothing has changed.
-  gfx::Vector2dF delegate_offset =
-      root_layer_scroll_offset_delegate_->GetTotalScrollOffset();
-  if (inner_viewport_offset + outer_viewport_offset == delegate_offset) {
-    if (layer == InnerViewportScrollLayer())
-      return inner_viewport_offset;
-    else
-      return outer_viewport_offset;
-  }
-
-  gfx::Vector2d max_outer_viewport_scroll_offset =
-    OuterViewportScrollLayer()->MaxScrollOffset();
-
-  outer_viewport_offset  = delegate_offset - inner_viewport_offset;
-  outer_viewport_offset.SetToMin(max_outer_viewport_scroll_offset);
-  outer_viewport_offset.SetToMax(gfx::Vector2d());
-
-  if (layer == OuterViewportScrollLayer())
-    return outer_viewport_offset;
-
-  inner_viewport_offset = delegate_offset - outer_viewport_offset;
-
-  return inner_viewport_offset;
-}
-
-// TODO(wjmaclean) Rename this function, as we no longer have a
-// "RootScrollLayer".
+  }
+}
+
 void LayerTreeImpl::UpdateRootScrollLayerSizeDelta() {
-  // TODO(wjmaclean) verify this is really the right thing to do in cases where
-  // the pinch virtual viewport is active.
-  LayerImpl* root_scroll = InnerViewportScrollLayer();
+  LayerImpl* root_scroll = RootScrollLayer();
   LayerImpl* root_container = RootContainerLayer();
   DCHECK(root_scroll);
   DCHECK(root_container);