Added std:: for libstdc++ compatibility

ios/chrome/browser/snapshots/snapshot_manager.mm

 // 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.
 
 #import "ios/chrome/browser/snapshots/snapshot_manager.h"
 
 #import <QuartzCore/QuartzCore.h>
 
 #include "base/logging.h"
 #import "ios/chrome/browser/snapshots/snapshot_cache.h"
 #import "ios/chrome/browser/snapshots/snapshot_overlay.h"
 
 @implementation SnapshotManager
 
 - (UIImage*)generateSnapshotForView:(UIView*)view
                            withRect:(CGRect)rect
                            overlays:(NSArray*)overlays {
   DCHECK(view);
   CGSize size = rect.size;
-  DCHECK(isnormal(size.width) && (size.width > 0))
+  DCHECK(std::isnormal(size.width) && (size.width > 0))
       << ": size.width=" << size.width;
-  DCHECK(isnormal(size.height) && (size.height > 0))
+  DCHECK(std::isnormal(size.height) && (size.height > 0))
       << ": size.height=" << size.height;
   const CGFloat kScale = [SnapshotCache snapshotScaleForDevice];
   UIGraphicsBeginImageContextWithOptions(size, YES, kScale);
   CGContext* context = UIGraphicsGetCurrentContext();
   if (!context) {
     NOTREACHED();
     return nil;
   }
 
   CGContextSaveGState(context);
@@ skipping 55 matching lines @@
   [[SnapshotCache sharedInstance] removeImageWithSessionID:sessionID];
 }
 
 - (void)greyImageForSessionID:(NSString*)sessionID
                      callback:(void (^)(UIImage*))callback {
   [[SnapshotCache sharedInstance] greyImageForSessionID:sessionID
                                                callback:callback];
 }
 
 @end