gfx: Make conversions from Size to SizeF be explicit.

cc/input/page_scale_animation.cc

 // Copyright 2012 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/input/page_scale_animation.h"
 
 #include <math.h>
 
 #include "base/logging.h"
 #include "cc/animation/timing_function.h"
@@ skipping 129 matching lines @@
   gfx::Vector2dF normalized = gfx::ScaleVector2d(
       start_scroll_offset_ - target_scroll_offset_, width_scale, height_scale);
   target_anchor_ =
       target_scroll_offset_ + DenormalizeToViewport(normalized,
                                                     TargetViewportSize());
 }
 
 void PageScaleAnimation::ClampTargetScrollOffset() {
   gfx::Vector2dF max_scroll_offset =
       gfx::RectF(root_layer_size_).bottom_right() -
-      gfx::RectF(TargetViewportSize()).bottom_right();
+      gfx::RectF(gfx::SizeF(TargetViewportSize())).bottom_right();
   target_scroll_offset_.SetToMax(gfx::Vector2dF());
   target_scroll_offset_.SetToMin(max_scroll_offset);
 }
 
 gfx::SizeF PageScaleAnimation::StartViewportSize() const {
   return gfx::ScaleSize(viewport_size_, 1.f / start_page_scale_factor_);
 }
 
 gfx::SizeF PageScaleAnimation::TargetViewportSize() const {
   return gfx::ScaleSize(viewport_size_, 1.f / target_page_scale_factor_);
@@ skipping 75 matching lines @@
 
   // Linearly interpolate the magnitude in log scale.
   float diff = target_page_scale_factor_ / start_page_scale_factor_;
   float log_diff = log(diff);
   log_diff *= interp;
   diff = exp(log_diff);
   return start_page_scale_factor_ * diff;
 }
 
 }  // namespace cc