Implement new overlay scrollbar specs

Make overlay scrollbars thicken only on mouse movement (not scrolling).
Keep the bars thick as long as the mouse is near them.
Thicken and darken the bars through an animation.
Make the distance to thicken the bars 25 dips (instead of 100).

BUG=299046,274010
R=enne@chromium.org, enne, tony

Review URL: https://codereview.chromium.org/40603006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@231118 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 8 insertions, 3 deletions

diff --git a/cc/layers/scrollbar_layer_impl_base.cc b/cc/layers/scrollbar_layer_impl_base.cc
index c1e7126..362465b 100644
--- a/cc/layers/scrollbar_layer_impl_base.cc
+++ b/cc/layers/scrollbar_layer_impl_base.cc
@@ -72,6 +72,13 @@ void ScrollbarLayerImplBase::SetVisibleToTotalLengthRatio(float ratio) {
   NoteLayerPropertyChanged();
 }
 
+void ScrollbarLayerImplBase::SetThumbThicknessScaleFactor(float factor) {
+  if (thumb_thickness_scale_factor_ == factor)
+    return;
+  thumb_thickness_scale_factor_ = factor;
+  NoteLayerPropertyChanged();
+}
+
 gfx::Rect ScrollbarLayerImplBase::ComputeThumbQuadRect() const {
   // Thumb extent is the length of the thumb in the scrolling direction, thumb
   // thickness is in the perpendicular direction. Here's an example of a
diff --git a/cc/layers/scrollbar_layer_impl_base.h b/cc/layers/scrollbar_layer_impl_base.h
index 55ade6a..360ef97 100644
--- a/cc/layers/scrollbar_layer_impl_base.h
+++ b/cc/layers/scrollbar_layer_impl_base.h
@@ -44,9 +44,7 @@ class CC_EXPORT ScrollbarLayerImplBase : public LayerImpl {
   float thumb_thickness_scale_factor() {
     return thumb_thickness_scale_factor_;
   }
-  void set_thumb_thickness_scale_factor(float thumb_thickness_scale_factor) {
-    thumb_thickness_scale_factor_ = thumb_thickness_scale_factor;
-  }
+  void SetThumbThicknessScaleFactor(float thumb_thickness_scale_factor);
 
  protected:
   ScrollbarLayerImplBase(LayerTreeImpl* tree_impl,