Refactor wait_util so it isn't coupled to EarlGrey.

ios/web/shell/test/pdf_egtest.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 <EarlGrey/EarlGrey.h>
 
 #include "base/test/ios/wait_util.h"
-#include "ios/testing/earl_grey/wait_util.h"
+#include "ios/testing/wait_util.h"
 #import "ios/web/public/test/earl_grey/web_view_matchers.h"
 #import "ios/web/public/test/http_server.h"
 #include "ios/web/public/test/http_server_util.h"
 #import "ios/web/shell/test/app/web_shell_test_util.h"
 #import "ios/web/shell/test/earl_grey/shell_base_test_case.h"
 #import "ios/web/shell/test/earl_grey/shell_earl_grey.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
 #endif
 
 namespace {
 // URL spec for test PDF page.
 const char kTestPDFURL[] =
     "http://ios/web/shell/test/http_server_files/testpage.pdf";
 
 // Matcher for WKWebView displaying PDF.
 id<GREYMatcher> webViewWithPdf() {
   web::WebState* web_state = web::shell_test_util::GetCurrentWebState();
   MatchesBlock matches = ^BOOL(UIView* view) {
-    __block BOOL did_succeed = NO;
-    NSDate* deadline =
-        [NSDate dateWithTimeIntervalSinceNow:testing::kWaitForUIElementTimeout];
-    while ([[NSDate date] compare:deadline] != NSOrderedDescending) {
-      if (web_state->GetContentsMimeType() == "application/pdf") {
-        did_succeed = YES;
-        break;
-      }
-      base::test::ios::SpinRunLoopWithMaxDelay(
-          base::TimeDelta::FromSecondsD(testing::kSpinDelaySeconds));
-    }
-    return did_succeed;
+    return testing::WaitUntilConditionOrTimeout(
+        testing::kWaitForUIElementTimeout, ^bool() {
+          return web_state->GetContentsMimeType() == "application/pdf";
+        });
   };
 
   DescribeToBlock describe = ^(id<GREYDescription> description) {
     [description appendText:@"web view with PDF"];
   };
 
   return grey_allOf(
       webViewInWebState(web_state),
       [[GREYElementMatcherBlock alloc] initWithMatchesBlock:matches
                                            descriptionBlock:describe],
@@ skipping 12 matching lines @@
 
 // Tests MIME type of the loaded PDF document.
 - (void)testMIMEType {
   web::test::SetUpFileBasedHttpServer();
   [ShellEarlGrey loadURL:HttpServer::MakeUrl(kTestPDFURL)];
   [[EarlGrey selectElementWithMatcher:webViewWithPdf()]
       assertWithMatcher:grey_notNil()];
 }
 
 @end