Ignore rounding error between clip_layer_length_ and scroll_layer_length_

cc/layers/scrollbar_layer_impl_base.cc

Index: cc/layers/scrollbar_layer_impl_base.cc
diff --git a/cc/layers/scrollbar_layer_impl_base.cc b/cc/layers/scrollbar_layer_impl_base.cc
index da53036fea0a07cd555c932d769ce32092f6aa19..41ad45f64349aa8d3e42dd2431781345bc4f926a 100644
--- a/cc/layers/scrollbar_layer_impl_base.cc
+++ b/cc/layers/scrollbar_layer_impl_base.cc
@@ -66,8 +66,17 @@ bool ScrollbarLayerImplBase::CanScrollOrientation() const {
   LayerImpl* scroll_layer = layer_tree_impl()->LayerById(scroll_layer_id_);
   if (!scroll_layer)
     return false;
+
+  float page_scale_factor = layer_tree_impl()->current_page_scale_factor();

[bokan, 2017/04/18 17:39:08]

I don't think this is right, why'd you add page scale from the previous patch?
The page scale factor is already applied as needed from UpdateScrollbars.
Further, it should only be applied for viewport scrollbars. This looked fine to
me in the previous patch.

+  float device_scale_factor = layer_tree_impl()->device_scale_factor();
+
+  int clip_layer_length =
+      std::ceil(clip_layer_length_ * page_scale_factor * device_scale_factor);
+  int scroll_layer_length =
+      std::ceil(scroll_layer_length_ * page_scale_factor * device_scale_factor);
+
   return scroll_layer->user_scrollable(orientation()) &&
-         clip_layer_length_ < scroll_layer_length_;
+         clip_layer_length < scroll_layer_length;
 }
 
 bool ScrollbarLayerImplBase::SetVerticalAdjust(float vertical_adjust) {