[Payment Request] Picker view + showcase integration + egtests

ios/showcase/common/protocol_alerter.mm

 // Copyright 2016 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/showcase/common/protocol_alerter.h"
 
 #import <objc/runtime.h>
 
 #import "base/logging.h"
 #import "base/strings/sys_string_conversions.h"
@@ skipping 152 matching lines @@
       return [self longLongDescriptionAtIndex:index];
     // Add cases as needed here.
     default:
       return [NSString stringWithFormat:@"<Unknown Type:%s>", type];
   }
 }
 
 // Return a string describing an argument at |index| that's known to be an
 // objective-C object.
 - (NSString*)objectDescriptionAtIndex:(NSInteger)index {
-  id object;
+  __unsafe_unretained id object;
 
   [self getArgument:&object atIndex:index];
   if (!object)
     return @"nil";
 
   NSString* description = [object description];
   NSString* className = NSStringFromClass([object class]);
   if (!description) {
     return
         [NSString stringWithFormat:@"<%@ object, no description>", className];
@@ skipping 20 matching lines @@
 // Returns a string describing an argument at |index| that is known to be a long
 // long.
 - (NSString*)longLongDescriptionAtIndex:(NSInteger)index {
   long long value;
 
   [self getArgument:&value atIndex:index];
   return [NSString stringWithFormat:@"%lld", value];
 }
 
 @end