[chromedriver] Use data:, instead of about:blank for the start page.

chrome/test/chromedriver/chrome_launcher.cc

 // Copyright (c) 2013 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 "chrome/test/chromedriver/chrome_launcher.h"
 
 #include <algorithm>
 #include <vector>
 
 #include "base/base64.h"
@@ skipping 97 matching lines @@
 
   for (std::set<std::string>::const_iterator iter =
            capabilities.exclude_switches.begin();
        iter != capabilities.exclude_switches.end();
        ++iter) {
     switches.RemoveSwitch(*iter);
   }
   switches.SetFromSwitches(capabilities.switches);
 
   if (!switches.HasSwitch("user-data-dir")) {
-    command.AppendArg("about:blank");
+    command.AppendArg("data:,");
     if (!user_data_dir->CreateUniqueTempDir())
       return Status(kUnknownError, "cannot create temp dir for user data dir");
     switches.SetSwitch("user-data-dir", user_data_dir->path().value());
     Status status = internal::PrepareUserDataDir(
         user_data_dir->path(), capabilities.prefs.get(),
         capabilities.local_state.get());
     if (status.IsError())
       return status;
   }
 
@@ skipping 464 matching lines @@
   // Write empty "First Run" file, otherwise Chrome will wipe the default
   // profile that was written.
   if (file_util::WriteFile(
           user_data_dir.AppendASCII("First Run"), "", 0) != 0) {
     return Status(kUnknownError, "failed to write first run file");
   }
   return Status(kOk);
 }
 
 }  // namespace internal