win: Add and use GET_FUNCTION() and GET_FUNCTION_REQUIRED()

util/win/process_info.cc

 // Copyright 2015 The Crashpad Authors. All rights reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
 #include "util/win/process_info.h"
 
 #include <winternl.h>
 
 #include <algorithm>
 #include <limits>
 
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/strings/stringprintf.h"
 #include "base/template_util.h"
 #include "build/build_config.h"
 #include "util/numeric/safe_assignment.h"
+#include "util/win/get_function.h"
 #include "util/win/nt_internals.h"
 #include "util/win/ntstatus_logging.h"
 #include "util/win/process_structs.h"
 #include "util/win/scoped_handle.h"
 
 namespace crashpad {
 
 namespace {
 
 NTSTATUS NtQueryInformationProcess(HANDLE process_handle,
                                    PROCESSINFOCLASS process_information_class,
                                    PVOID process_information,
                                    ULONG process_information_length,
                                    PULONG return_length) {
-  static decltype(::NtQueryInformationProcess)* nt_query_information_process =
-      reinterpret_cast<decltype(::NtQueryInformationProcess)*>(GetProcAddress(
-          LoadLibrary(L"ntdll.dll"), "NtQueryInformationProcess"));
-  DCHECK(nt_query_information_process);
+  static const auto nt_query_information_process =
+      GET_FUNCTION_REQUIRED(L"ntdll.dll", ::NtQueryInformationProcess);
   return nt_query_information_process(process_handle,
                                       process_information_class,
                                       process_information,
                                       process_information_length,
                                       return_length);
 }
 
 bool IsProcessWow64(HANDLE process_handle) {
-  static decltype(IsWow64Process)* is_wow64_process =
-      reinterpret_cast<decltype(IsWow64Process)*>(
-          GetProcAddress(LoadLibrary(L"kernel32.dll"), "IsWow64Process"));
+  static const auto is_wow64_process =
+      GET_FUNCTION(L"kernel32.dll", ::IsWow64Process);
   if (!is_wow64_process)
     return false;
   BOOL is_wow64;
   if (!is_wow64_process(process_handle, &is_wow64)) {
     PLOG(ERROR) << "IsWow64Process";
     return false;
   }
   return is_wow64;
 }
 
@@ skipping 598 matching lines @@
     } else {
       result.push_back(as_ranges[i]);
     }
     DCHECK(result.back().IsValid());
   }
 
   return result;
 }
 
 }  // namespace crashpad