clang/win: Let remaining chromium_code targets build with -Wextra.

sandbox/win/src/handle_closer_agent.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 "sandbox/win/src/handle_closer_agent.h"
 
 #include "base/logging.h"
 #include "sandbox/win/src/nt_internals.h"
 #include "sandbox/win/src/win_utils.h"
 
@@ skipping 102 matching lines @@
       CHECK(name.second);
       input += name.first->size() + 1;
     }
 
     // Move on to the next entry.
     entry = reinterpret_cast<HandleListEntry*>(reinterpret_cast<char*>(entry)
         + entry->record_bytes);
 
     DCHECK(reinterpret_cast<base::char16*>(entry) >= input);
     DCHECK(reinterpret_cast<base::char16*>(entry) - input <
-           sizeof(size_t) / sizeof(base::char16));
+           static_cast<ptrdiff_t>(sizeof(size_t) / sizeof(base::char16)));
   }
 
   // Clean up the memory we copied over.
   ::VirtualFree(g_handles_to_close, 0, MEM_RELEASE);
   g_handles_to_close = NULL;
 }
 
 bool HandleCloserAgent::CloseHandles() {
   DWORD handle_count = UINT_MAX;
   const int kInvalidHandleThreshold = 100;
@@ skipping 57 matching lines @@
         return false;
       // Attempt to stuff this handle with a new dummy Event.
       AttemptToStuffHandleSlot(handle, result->first);
     }
   }
 
   return true;
 }
 
 }  // namespace sandbox