Refactor wait_util so it isn't coupled to EarlGrey.

ios/testing/wait_util.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.
 
-#include "ios/testing/earl_grey/wait_util.h"
-
-#import <EarlGrey/EarlGrey.h>
+#import "ios/testing/wait_util.h"
 
 #include "base/test/ios/wait_util.h"
 
 namespace testing {
 
 const NSTimeInterval kSpinDelaySeconds = 0.01;
 const NSTimeInterval kWaitForJSCompletionTimeout = 2.0;
 const NSTimeInterval kWaitForUIElementTimeout = 4.0;
 const NSTimeInterval kWaitForDownloadTimeout = 10.0;
 
-void WaitUntilCondition(NSTimeInterval timeout,
-                        NSString* timeoutDescription,
-                        bool (^condition)(void)) {
+bool WaitUntilConditionOrTimeout(NSTimeInterval timeout,
+                                 ConditionBlock condition) {
   NSDate* deadline = [NSDate dateWithTimeIntervalSinceNow:timeout];
-  while (!condition() &&
-         [[NSDate date] compare:deadline] != NSOrderedDescending) {
+  bool success = condition();
+  while (!success && [[NSDate date] compare:deadline] != NSOrderedDescending) {
     base::test::ios::SpinRunLoopWithMaxDelay(
         base::TimeDelta::FromSecondsD(testing::kSpinDelaySeconds));
+    success = condition();
   }
-  GREYAssert(condition(), timeoutDescription);
-}
-
-void WaitUntilCondition(NSTimeInterval timeout, bool (^condition)(void)) {
-  WaitUntilCondition(timeout, @"Timeout waiting for condition.", condition);
+  return success;
 }
 
 }  // namespace testing