[Sky] Fix iOS build breaks

sky/shell/ios/sky_surface.mm

 // 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.
 
 #import "sky_surface.h"
 
 #import <QuartzCore/QuartzCore.h>
 #import <OpenGLES/EAGL.h>
 #import <OpenGLES/EAGLDrawable.h>
 
@@ skipping 68 matching lines @@
 - (void)layoutSubviews {
   [super layoutSubviews];
 
   [self configureLayerDefaults];
 
   [self setupPlatformViewIfNecessary];
 
   CGSize size = self.bounds.size;
   CGFloat scale = [UIScreen mainScreen].scale;
 
-  ViewportMetricsPtr metrics = ViewportMetrics::New();
+  sky::ViewportMetricsPtr metrics = sky::ViewportMetrics::New();
   metrics->physical_width = size.width * scale;
   metrics->physical_height = size.height * scale;
   metrics->device_pixel_ratio = scale;
   _sky_engine->OnViewportMetricsChanged(metrics.Pass());
 }
 
 - (void)configureLayerDefaults {
   CAEAGLLayer* layer = reinterpret_cast<CAEAGLLayer*>(self.layer);
   layer.allowsGroupOpacity = YES;
   layer.opaque = YES;
@@ skipping 189 matching lines @@
 + (Class)layerClass {
   return [CAEAGLLayer class];
 }
 
 - (void)dealloc {
   [self notifySurfaceDestruction];
   [super dealloc];
 }
 
 @end