Fixed all unused-variable Clang warnings on Windows.

components/crash/app/breakpad_win.cc

 // Copyright 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 "components/crash/app/breakpad_win.h"
 
 #include <windows.h>
 #include <shellapi.h>
 #include <tchar.h>
 #include <userenv.h>
@@ skipping 76 matching lines @@
 
 const wchar_t kGoogleUpdatePipeName[] = L"\\\\.\\pipe\\GoogleCrashServices\\";
 const wchar_t kChromePipeName[] = L"\\\\.\\pipe\\ChromeCrashServices";
 
 // This is the well known SID for the system principal.
 const wchar_t kSystemPrincipalSid[] =L"S-1-5-18";
 
 google_breakpad::ExceptionHandler* g_breakpad = NULL;
 google_breakpad::ExceptionHandler* g_dumphandler_no_crash = NULL;
 
+#if !defined(_WIN64)
 EXCEPTION_POINTERS g_surrogate_exception_pointers = {0};
 EXCEPTION_RECORD g_surrogate_exception_record = {0};
 CONTEXT g_surrogate_context = {0};
+#endif  // !defined(_WIN64)
 
 typedef NTSTATUS (WINAPI* NtTerminateProcessPtr)(HANDLE ProcessHandle,
                                                  NTSTATUS ExitStatus);
 char* g_real_terminate_process_stub = NULL;
 
 }  // namespace
 
 // Dumps the current process memory.
 extern "C" void __declspec(dllexport) __cdecl DumpProcess() {
   if (g_breakpad) {
@@ skipping 622 matching lines @@
 extern "C" void __declspec(dllexport) __cdecl
 UnregisterNonABICompliantCodeRange(void* start) {
   ExceptionHandlerRecord* record =
       reinterpret_cast<ExceptionHandlerRecord*>(start);
 
   CHECK(RtlDeleteFunctionTable(&record->runtime_function));
 }
 #endif
 
 }  // namespace breakpad