Avoid incrementing an invalid iterator in the utility process client.

chrome/utility/chrome_content_utility_client.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 "chrome/utility/chrome_content_utility_client.h"
 
 #include <stddef.h>
 #include <utility>
 
 #include "base/command_line.h"
@@ skipping 157 matching lines @@
     IPC_MESSAGE_HANDLER(ChromeUtilityMsg_AnalyzeDmgFileForDownloadProtection,
                         OnAnalyzeDmgFileForDownloadProtection)
 #endif  // defined(OS_MACOSX)
 #endif  // defined(FULL_SAFE_BROWSING)
 #if defined(OS_CHROMEOS)
     IPC_MESSAGE_HANDLER(ChromeUtilityMsg_CreateZipFile, OnCreateZipFile)
 #endif
     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP()
 
-  for (Handlers::iterator it = handlers_.begin();
-       !handled && it != handlers_.end(); ++it) {
-    handled = (*it)->OnMessageReceived(message);
+  if (handled)
+    return true;
+
+  for (const auto& handler : handlers_) {
+    // At least one of the utility process handlers adds a new handler to
+    // |handlers_| when it handles a message. This causes any iterator over
+    // |handlers_| to become invalid. Therefore, it is necessary to break the
+    // loop at this point instead of evaluating it as a loop condition (if the
+    // for loop was using iterators explicitly, as originally done).
+    if (handler->OnMessageReceived(message))
+      return true;
   }
 
-  return handled;
+  return false;
 }
 
 void ChromeContentUtilityClient::RegisterMojoServices(
     content::ServiceRegistry* registry) {
   // When the utility process is running with elevated privileges, we need to
   // filter messages so that only a whitelist of IPCs can run. In Mojo, there's
   // no way of filtering individual messages. Instead, we can avoid adding
   // non-whitelisted Mojo services to the ServiceRegistry.
   // TODO(amistry): Use a whitelist once the whistlisted IPCs have been
   // converted to Mojo.
@@ skipping 102 matching lines @@
   safe_browsing::zip_analyzer::Results results;
   safe_browsing::dmg::AnalyzeDMGFile(
       IPC::PlatformFileForTransitToFile(dmg_file), &results);
   Send(new ChromeUtilityHostMsg_AnalyzeDmgFileForDownloadProtection_Finished(
       results));
   ReleaseProcessIfNeeded();
 }
 #endif  // defined(OS_MACOSX)
 
 #endif  // defined(FULL_SAFE_BROWSING)