Create EarlGrey wait utility.

ios/web/shell/test/earl_grey/shell_matchers.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/web/shell/test/earl_grey/shell_matchers.h"
 
 #import "base/mac/foundation_util.h"
 #include "base/strings/sys_string_conversions.h"
 #include "base/test/ios/wait_util.h"
 #include "ios/testing/earl_grey/wait_util.h"
@@ skipping 36 matching lines @@
 + (id<GREYMatcher>)matcherForAddressFieldEqualToText:(const std::string&)text {
   MatchesBlock matches = ^BOOL(UIView* view) {
     if (![view isKindOfClass:[UITextField class]]) {
       return NO;
     }
     if (![[view accessibilityLabel]
             isEqualToString:kWebShellAddressFieldAccessibilityLabel]) {
       return NO;
     }
     UITextField* textField = base::mac::ObjCCastStrict<UITextField>(view);
-    NSDate* deadline =
-        [NSDate dateWithTimeIntervalSinceNow:testing::kWaitForUIElementTimeout];
-    while ([[NSDate date] compare:deadline] != NSOrderedDescending) {
-      if ([textField.text isEqualToString:base::SysUTF8ToNSString(text)]) {
-        return YES;
-      }
-      base::test::ios::SpinRunLoopWithMaxDelay(
-          base::TimeDelta::FromSecondsD(testing::kSpinDelaySeconds));
-    }
-    return NO;
+    testing::WaitUntilCondition(testing::kWaitForUIElementTimeout, ^bool() {
+      return [textField.text isEqualToString:base::SysUTF8ToNSString(text)];
+    });
+    return YES;
   };
 
   DescribeToBlock describe = ^(id<GREYDescription> description) {
     [description appendText:@"address field containing "];
     [description appendText:base::SysUTF8ToNSString(text)];
   };
 
   return [[[GREYElementMatcherBlock alloc] initWithMatchesBlock:matches
                                                descriptionBlock:describe]
       autorelease];
 }
 
 + (id<GREYMatcher>)matcherForWebShellBackButton {
   return grey_accessibilityLabel(kWebShellBackButtonAccessibilityLabel);
 }
 
 + (id<GREYMatcher>)matcherForWebShellForwardButton {
   return grey_accessibilityLabel(kWebShellForwardButtonAccessibilityLabel);
 }
 
 + (id<GREYMatcher>)matcherForWebShellAddressField {
   return grey_accessibilityLabel(kWebShellAddressFieldAccessibilityLabel);
 }
 
 @end