Extract the mini_installer's entrypoint into its own source file.

chrome/installer/mini_installer/mini_installer.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.
 
 // mini_installer.exe is the first exe that is run when chrome is being
 // installed or upgraded. It is designed to be extremely small (~5KB with no
 // extra resources linked) and it has two main jobs:
 //   1) unpack the resources (possibly decompressing some)
 //   2) run the real installer (setup.exe) with appropriate flags.
 //
 // In order to be really small the app doesn't link against the CRT and
 // defines the following compiler/linker flags:
 //   EnableIntrinsicFunctions="true" compiler: /Oi
 //   BasicRuntimeChecks="0"
 //   BufferSecurityCheck="false" compiler: /GS-
 //   EntryPointSymbol="MainEntryPoint" linker: /ENTRY
 //   IgnoreAllDefaultLibraries="true" linker: /NODEFAULTLIB
 //   OptimizeForWindows98="1" linker: /OPT:NOWIN98
 //   linker: /SAFESEH:NO
 
 // have the linker merge the sections, saving us ~500 bytes.
 #pragma comment(linker, "/MERGE:.rdata=.text")
 
+#include "chrome/installer/mini_installer/mini_installer.h"
+
 #include <windows.h>
 
 // #define needed to link in RtlGenRandom(), a.k.a. SystemFunction036.  See the
 // "Community Additions" comment on MSDN here:
 // http://msdn.microsoft.com/en-us/library/windows/desktop/aa387694.aspx
 #define SystemFunction036 NTAPI SystemFunction036
 #include <NTSecAPI.h>
 #undef SystemFunction036
 
 #include <sddl.h>
 #include <shellapi.h>
 #include <stdlib.h>
 #include <stddef.h>
 
 #include "chrome/installer/mini_installer/appid.h"
 #include "chrome/installer/mini_installer/configuration.h"
 #include "chrome/installer/mini_installer/decompress.h"
-#include "chrome/installer/mini_installer/exit_code.h"
 #include "chrome/installer/mini_installer/mini_installer_constants.h"
 #include "chrome/installer/mini_installer/mini_string.h"
 #include "chrome/installer/mini_installer/pe_resource.h"
 #include "chrome/installer/mini_installer/regkey.h"
 
 namespace mini_installer {
 
 typedef StackString<MAX_PATH> PathString;
 typedef StackString<MAX_PATH * 4> CommandString;
 
-struct ProcessExitResult {
-  DWORD exit_code;
-  DWORD windows_error;
-
-  explicit ProcessExitResult(DWORD exit) : exit_code(exit), windows_error(0) {}
-  ProcessExitResult(DWORD exit, DWORD win)
-      : exit_code(exit), windows_error(win) {
-  }
-
-  bool IsSuccess() {
-    return exit_code == SUCCESS_EXIT_CODE;
-  }
-};
-
 // This structure passes data back and forth for the processing
 // of resource callbacks.
 struct Context {
   // Input to the call back method. Specifies the dir to save resources.
   const wchar_t* base_path;
   // First output from call back method. Full path of Chrome archive.
   PathString* chrome_resource_path;
   // Second output from call back method. Full path of Setup archive/exe.
   PathString* setup_resource_path;
 };
@@ skipping 740 matching lines @@
   wchar_t value[2] = {0};
   if (RegKey::ReadSZValue(HKEY_CURRENT_USER, kCleanupRegistryKey,
                           kCleanupRegistryValue, value, _countof(value)) &&
       value[0] == L'0') {
     return false;
   }
 
   return true;
 }
 
-// Main function. First gets a working dir, unpacks the resources and finally
-// executes setup.exe to do the install/upgrade.
 ProcessExitResult WMain(HMODULE module) {
   // Always start with deleting potential leftovers from previous installations.
   // This can make the difference between success and failure.  We've seen
   // many installations out in the field fail due to out of disk space problems
   // so this could buy us some space.
   DeleteOldChromeTempDirectories();
 
   ProcessExitResult exit_code = ProcessExitResult(SUCCESS_EXIT_CODE);
 
   // Parse configuration from the command line and resources.
@@ skipping 42 matching lines @@
     DeleteExtractedFiles(base_path.get(), archive_path.get(), setup_path.get());
 
 #if defined(GOOGLE_CHROME_BUILD)
   WriteInstallResults(configuration, exit_code);
 #endif
 
   return exit_code;
 }
 
 }  // namespace mini_installer
-
-int MainEntryPoint() {
-  mini_installer::ProcessExitResult result =
-      mini_installer::WMain(::GetModuleHandle(NULL));
-
-  ::ExitProcess(result.exit_code);
-}
-
-#if defined(ADDRESS_SANITIZER)
-// Executables instrumented with ASAN need CRT functions. We do not use
-// the /ENTRY switch for ASAN instrumented executable and a "main" function
-// is required.
-int WINAPI WinMain(HINSTANCE hInstance,
-                   HINSTANCE hPrevInstance,
-                   LPSTR lpCmdLine,
-                   int nCmdShow) {
-  MainEntryPoint();
-  return 0;
-}
-#endif
-
-// VC Express editions don't come with the memset CRT obj file and linking to
-// the obj files between versions becomes a bit problematic. Therefore,
-// simply implement memset.
-//
-// This also avoids having to explicitly set the __sse2_available hack when
-// linking with both the x64 and x86 obj files which is required when not
-// linking with the std C lib in certain instances (including Chromium) with
-// MSVC.  __sse2_available determines whether to use SSE2 intructions with
-// std C lib routines, and is set by MSVC's std C lib implementation normally.
-extern "C" {
-#pragma function(memset)
-void* memset(void* dest, int c, size_t count) {
-  void* start = dest;
-  while (count--) {
-    *reinterpret_cast<char*>(dest) = static_cast<char>(c);
-    dest = reinterpret_cast<char*>(dest) + 1;
-  }
-  return start;
-}
-}  // extern "C"