Don't register or use the DelegateExecute verb handler if it isn't present.

chrome/installer/util/install_util.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.
 //
 // See the corresponding header file for description of the functions in this
 // file.
 
 #include "chrome/installer/util/install_util.h"
 
 #include <shellapi.h>
 #include <shlobj.h>
 #include <shlwapi.h>
 
 #include <algorithm>
 
 #include "base/command_line.h"
+#include "base/file_util.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/path_service.h"
 #include "base/string_util.h"
 #include "base/sys_info.h"
 #include "base/values.h"
 #include "base/version.h"
 #include "base/win/registry.h"
 #include "base/win/windows_version.h"
 #include "chrome/installer/util/browser_distribution.h"
@@ skipping 304 matching lines @@
                                           installer::kInstallBinaryDir) &&
          FilePath::CompareEqualIgnoreCase(exe_dir.DirName().BaseName().value(),
                                           chrome_sxs_dir);
 }
 
 bool InstallUtil::IsChromeSxSProcess() {
   static bool sxs = CheckIsChromeSxSProcess();
   return sxs;
 }
 
+bool InstallUtil::HasDelegateExecuteHandler(BrowserDistribution* dist,
+                                            const string16& chrome_exe) {
+  bool found = false;
+  bool system_install = !IsPerUserInstall(chrome_exe.c_str());
+  scoped_ptr<Version> version(GetChromeVersion(dist, system_install));
+  if (!version.get()) {
+    LOG(ERROR) << __FUNCTION__ << " failed to determine version of "
+               << dist->GetAppShortCutName() << " installed at " << chrome_exe;
+  } else {
+    FilePath handler(
+        FilePath(chrome_exe).DirName()
+            .AppendASCII(version->GetString())
+            .Append(installer::kDelegateExecuteExe));
+    found = file_util::PathExists(handler);
+  }
+  return found;
+}
+
 // This method tries to delete a registry key and logs an error message
 // in case of failure. It returns true if deletion is successful,
 // otherwise false.
 bool InstallUtil::DeleteRegistryKey(HKEY root_key,
                                     const std::wstring& key_path) {
   VLOG(1) << "Deleting registry key " << key_path;
   LONG result = ::SHDeleteKey(root_key, key_path.c_str());
   if (result != ERROR_SUCCESS && result != ERROR_FILE_NOT_FOUND) {
     LOG(ERROR) << "Failed to delete registry key: " << key_path
                << " error: " << result;
@@ skipping 101 matching lines @@
   int len = GetDateFormatW(LOCALE_INVARIANT, 0, NULL, kDateFormat,
                            date_str, arraysize(date_str));
   if (len) {
     --len;  // Subtract terminating \0.
   } else {
     PLOG(DFATAL) << "GetDateFormat";
   }
 
   return std::wstring(date_str, len);
 }