Change iOS web matcher argument types to std::string.

ios/web/public/test/earl_grey/web_view_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/public/test/earl_grey/web_view_matchers.h"
 
 #import <WebKit/WebKit.h>
 
 #include "base/mac/bind_objc_block.h"
 #include "base/strings/sys_string_conversions.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/test/ios/wait_util.h"
 #include "base/values.h"
 #include "ios/testing/earl_grey/wait_util.h"
 
 namespace {
 
 // Script that returns document.body as a string.
 char kGetDocumentBodyJavaScript[] =
     "document.body ? document.body.textContent : null";
 }
 
 namespace web {
 
 id<GREYMatcher> webViewContainingText(NSString* text, web::WebState* webState) {
+  return [GREYMatchers
+      matcherForWebViewContainingText:base::SysNSStringToUTF8(text)
+                           inWebState:webState];
+}
+
+id<GREYMatcher> webViewContainingText(const std::string& text,
+                                      web::WebState* webState) {
   return
       [GREYMatchers matcherForWebViewContainingText:text inWebState:webState];
 }
 
 }  // namespace web
 
 @implementation GREYMatchers (WebViewAdditions)
 
-+ (id<GREYMatcher>)matcherForWebViewContainingText:(NSString*)text
++ (id<GREYMatcher>)matcherForWebViewContainingText:(const std::string&)text
                                         inWebState:(web::WebState*)webState {
   MatchesBlock matches = ^BOOL(UIView* view) {
     if (![view isKindOfClass:[WKWebView class]]) {
       return NO;
     }
     if (![view isDescendantOfView:webState->GetView()]) {
       return NO;
     }
 
     __block BOOL didSucceed = NO;
     NSDate* deadline =
         [NSDate dateWithTimeIntervalSinceNow:testing::kWaitForUIElementTimeout];
     while (([[NSDate date] compare:deadline] != NSOrderedDescending) &&
            !didSucceed) {
       webState->ExecuteJavaScript(
           base::UTF8ToUTF16(kGetDocumentBodyJavaScript),
           base::BindBlock(^(const base::Value* value) {
             std::string response;
             if (value && value->IsType(base::Value::TYPE_STRING) &&
                 value->GetAsString(&response)) {
-              didSucceed = response.find(base::SysNSStringToUTF8(text)) !=
-                           std::string::npos;
+              didSucceed = response.find(text) != std::string::npos;
             }
           }));
       base::test::ios::SpinRunLoopWithMaxDelay(
           base::TimeDelta::FromSecondsD(testing::kSpinDelaySeconds));
     }
     return didSucceed;
   };
 
   DescribeToBlock describe = ^(id<GREYDescription> description) {
-    [description
-        appendText:[NSString stringWithFormat:@"web view containing %@", text]];
+    [description appendText:@"web view containing "];
+    [description appendText:base::SysUTF8ToNSString(text)];
   };
 
   return [[[GREYElementMatcherBlock alloc] initWithMatchesBlock:matches
                                                descriptionBlock:describe]
       autorelease];
 }
 
 @end