gfx: Make conversions from Size to SizeF be explicit.

cc/layers/viewport.cc

 // Copyright 2015 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/layers/viewport.h"
 
 #include "base/logging.h"
 #include "cc/input/top_controls_manager.h"
 #include "cc/trees/layer_tree_host_impl.h"
 #include "cc/trees/layer_tree_impl.h"
@@ skipping 49 matching lines @@
                                                      viewport_point,
                                                      is_direct_manipulation);
     result.consumed_delta = delta - AdjustOverscroll(pending_content_delta);
   }
 
   result.content_scrolled_delta = content_delta - pending_content_delta;
   return result;
 }
 
 void Viewport::SnapPinchAnchorIfWithinMargin(const gfx::Point& anchor) {
-  gfx::SizeF viewport_size =
-      host_impl_->active_tree()->InnerViewportContainerLayer()->bounds();
+  gfx::SizeF viewport_size = gfx::SizeF(
+      host_impl_->active_tree()->InnerViewportContainerLayer()->bounds());
 
   if (anchor.x() < kPinchZoomSnapMarginDips)
     pinch_anchor_adjustment_.set_x(-anchor.x());
   else if (anchor.x() > viewport_size.width() - kPinchZoomSnapMarginDips)
     pinch_anchor_adjustment_.set_x(viewport_size.width() - anchor.x());
 
   if (anchor.y() < kPinchZoomSnapMarginDips)
     pinch_anchor_adjustment_.set_y(-anchor.y());
   else if (anchor.y() > viewport_size.height() - kPinchZoomSnapMarginDips)
     pinch_anchor_adjustment_.set_y(viewport_size.height() - anchor.y());
@@ skipping 97 matching lines @@
 
 LayerImpl* Viewport::InnerScrollLayer() const {
   return host_impl_->InnerViewportScrollLayer();
 }
 
 LayerImpl* Viewport::OuterScrollLayer() const {
   return host_impl_->OuterViewportScrollLayer();
 }
 
 }  // namespace cc