Make various string_util functions take StringPieces instead of char[].

chrome/browser/errorpage_browsertest.cc

 // Copyright (c) 2012 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 "base/bind.h"
 #include "base/command_line.h"
 #include "base/compiler_specific.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
@@ skipping 71 matching lines @@
       browser->tab_strip_model()->GetActiveWebContents(),
       "document.getElementById('more-less-button').click();"));
 }
 
 // Returns true if |browser| is displaying the text representation of
 // |error_code| on the current page.
 bool WARN_UNUSED_RESULT IsDisplayingNetError(Browser* browser,
                                              net::Error error_code) {
   // Get the error as a string, and remove the leading "net::", which is not
   // included on error pages.
-  std::string error_string = net::ErrorToString(error_code);
-  base::RemoveChars(error_string, "net:", &error_string);
+  std::string error_string(net::ErrorToString(error_code));
+  DCHECK(StartsWithASCII(error_string, "net::", true));
+  error_string.erase(0, 5);
 
   return IsDisplayingText(browser, error_string);
 }
 
 // Checks that the local error page is being displayed, without remotely
 // retrieved navigation corrections, and with the specified error code.
 void ExpectDisplayingLocalErrorPage(Browser* browser, net::Error error_code) {
   // Expand the help box so innerText will include text below the fold.
   ToggleHelpBox(browser);
 
@@ skipping 998 matching lines @@
       browser(),
       URLRequestFailedJob::GetMockHttpUrlForHostname(net::ERR_UNSAFE_PORT,
                                                      kHostname),
       1);
 
   ToggleHelpBox(browser());
   EXPECT_TRUE(IsDisplayingText(browser(), kHostnameJSUnicode));
 }
 
 }  // namespace