Make LayerScrollOffsetDelegate updates consistent.

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 b68e1d5436d041c5a8d2ed2c3b3827e3dfc3215a..313ac56f5fcdad84f4ceb9d421b7bd883649cc04 100644
--- a/cc/trees/layer_tree_impl.cc
+++ b/cc/trees/layer_tree_impl.cc
@@ -52,17 +52,14 @@ class LayerScrollOffsetDelegateProxy : public LayerScrollOffsetDelegate {
     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 SetTotalPageScaleFactorAndLimits(float, float, float) OVERRIDE {
-    NOTIMPLEMENTED();
-  }
-
-  virtual void SetScrollableSize(const gfx::SizeF& scrollable_size) OVERRIDE {
+  // This is never called by LayerImpl on its LayerScrollOffsetDelegate, and so
+  // has been left not implemented.
+  virtual void UpdateRootLayerState(const gfx::Vector2dF& total_scroll_offset,
+                                    const gfx::Vector2dF& max_scroll_offset,
+                                    const gfx::SizeF& scrollable_size,
+                                    float page_scale_factor,
+                                    float min_page_scale_factor,
+                                    float max_page_scale_factor) OVERRIDE {
     NOTIMPLEMENTED();
   }
 
@@ -304,7 +301,10 @@ void LayerTreeImpl::SetPageScaleFactorAndLimits(float page_scale_factor,
   page_scale_factor_ = page_scale_factor;
 
   if (root_layer_scroll_offset_delegate_) {
-    root_layer_scroll_offset_delegate_->SetTotalPageScaleFactorAndLimits(
+    root_layer_scroll_offset_delegate_->UpdateRootLayerState(
+        TotalScrollOffset(),
+        TotalMaxScrollOffset(),
+        ScrollableSize(),
         total_page_scale_factor(),
         this->min_page_scale_factor(),
         this->max_page_scale_factor());
@@ -338,7 +338,10 @@ void LayerTreeImpl::SetPageScaleDelta(float delta) {
   set_needs_update_draw_properties();
 
   if (root_layer_scroll_offset_delegate_) {
-    root_layer_scroll_offset_delegate_->SetTotalPageScaleFactorAndLimits(
+    root_layer_scroll_offset_delegate_->UpdateRootLayerState(
+        TotalScrollOffset(),
+        TotalMaxScrollOffset(),
+        ScrollableSize(),
         total_page_scale_factor(),
         min_page_scale_factor(),
         max_page_scale_factor());
@@ -763,12 +766,10 @@ void LayerTreeImpl::SetRootLayerScrollOffsetDelegate(
   root_layer_scroll_offset_delegate_ = 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_->SetTotalPageScaleFactorAndLimits(
+    root_layer_scroll_offset_delegate_->UpdateRootLayerState(
+        TotalScrollOffset(),
+        TotalMaxScrollOffset(),
+        ScrollableSize(),
         total_page_scale_factor(),
         min_page_scale_factor(),
         max_page_scale_factor());
@@ -803,9 +804,13 @@ void LayerTreeImpl::UpdateScrollOffsetDelegate() {
   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());
+  root_layer_scroll_offset_delegate_->UpdateRootLayerState(
+      offset,
+      TotalMaxScrollOffset(),
+      ScrollableSize(),
+      total_page_scale_factor(),
+      min_page_scale_factor(),
+      max_page_scale_factor());
 }
 
 gfx::Vector2dF LayerTreeImpl::GetDelegatedScrollOffset(LayerImpl* layer) {