Make scroll offset type of float in cc

cc/trees/layer_tree_host_common.cc

 // Copyright 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/trees/layer_tree_host_common.h"
 
 #include <algorithm>
 
 #include "base/debug/trace_event.h"
 #include "cc/base/math_util.h"
@@ skipping 34 matching lines @@
   // The scroll parent's scroll delta is the amount we've scrolled on the
   // compositor thread since the commit for this layer tree's source frame.
   // we last reported to the main thread. I.e., it's the discrepancy between
   // a scroll parent's scroll delta and offset, so we must add it here.
   if (layer->scroll_parent())
     scroll_delta += layer->scroll_parent()->ScrollDelta();
   return scroll_delta;
 }
 
 template <typename LayerType>
-static gfx::Vector2dF GetEffectiveTotalScrollOffset(LayerType* layer) {
-  gfx::Vector2dF offset = layer->TotalScrollOffset();
+static gfx::ScrollOffset GetEffectiveTotalScrollOffset(LayerType* layer) {
+  gfx::ScrollOffset offset = layer->TotalScrollOffset();
   // The scroll parent's total scroll offset (scroll offset + scroll delta)
   // can't be used because its scroll offset has already been applied to the
   // scroll children's positions by the main thread layer positioning code.
   if (layer->scroll_parent())
-    offset += layer->scroll_parent()->ScrollDelta();
+    offset += gfx::ScrollOffset(layer->scroll_parent()->ScrollDelta());
   return offset;
 }
 
 inline gfx::Rect CalculateVisibleRectWithCachedLayerRect(
     const gfx::Rect& target_surface_rect,
     const gfx::Rect& layer_bound_rect,
     const gfx::Rect& layer_rect_in_target_space,
     const gfx::Transform& transform) {
   if (layer_rect_in_target_space.IsEmpty())
     return gfx::Rect();
@@ skipping 1566 matching lines @@
 
   bool animating_transform_to_target = layer->TransformIsAnimating();
   bool animating_transform_to_screen = animating_transform_to_target;
   if (layer->parent()) {
     animating_transform_to_target |=
         layer->parent()->draw_transform_is_animating();
     animating_transform_to_screen |=
         layer->parent()->screen_space_transform_is_animating();
   }
   gfx::Point3F transform_origin = layer->transform_origin();
-  gfx::Vector2dF scroll_offset = GetEffectiveTotalScrollOffset(layer);
-  gfx::PointF position = layer->position() - scroll_offset;
+  gfx::ScrollOffset scroll_offset = GetEffectiveTotalScrollOffset(layer);
+  gfx::PointF position =
+      layer->position() - ScrollOffsetToVector2dF(scroll_offset);
   gfx::Transform combined_transform = data_from_ancestor.parent_matrix;
   if (!layer->transform().IsIdentity()) {
     // LT = Tr[origin] * Tr[origin2transformOrigin]
     combined_transform.Translate3d(position.x() + transform_origin.x(),
                                    position.y() + transform_origin.y(),
                                    transform_origin.z());
     // LT = Tr[origin] * Tr[origin2origin] * M[layer]
     combined_transform.PreconcatTransform(layer->transform());
     // LT = Tr[origin] * Tr[origin2origin] * M[layer] *
     // Tr[transformOrigin2origin]
@@ skipping 776 matching lines @@
       inputs->current_render_surface_layer_list_id);
 
   // The dummy layer list should not have been used.
   DCHECK_EQ(0u, dummy_layer_list.size());
   // A root layer render_surface should always exist after
   // CalculateDrawProperties.
   DCHECK(inputs->root_layer->render_surface());
 }
 
 }  // namespace cc