win handler: Provide a wmain() entry point

Crashpad’s own build always uses wWinMain(), the default entry point for
/subsystem:windows, producing crashpad_handler.exe. crashpad_handler.com
is a /subsystem:console version produced by running editbin on a copy of
crashpad_handler.exe. This leaves the entry point intact, so both copies
use wWinMain(). crashpad_handler.com does not use wmain() as
traditionally used by /subsystem:console programs.

For the in-Chromium build’s tests, it is conveient to produce the
/subsystem:console version, crashpad_handler.com, directly as linker
output, as opposed to using editbin to transform a /subsystem:windows
version. This /subsystem:console version uses the normal wmain() entry
point.

By providing both wWinMain() and wmain(), both build types can be
accommodated.

Bug: chromium:779790
Change-Id: Ieb784db0cc245c6e4c12fb1dd83b8b95e159bdec
Reviewed-on: https://chromium-review.googlesource.com/746161
Reviewed-by: Leonard Mosescu <mosescu@chromium.org>

handler/main.cc

@@ -22,10 +22,13 @@
 #endif
 
 #if defined(OS_MACOSX)
+
 int main(int argc, char* argv[]) {
   return crashpad::HandlerMain(argc, argv, nullptr);
 }
+
 #elif defined(OS_WIN)
+
 namespace {
 
 int HandlerMainAdaptor(int argc, char* argv[]) {
@@ -34,7 +37,17 @@ int HandlerMainAdaptor(int argc, char* argv[]) {
 
 }  // namespace
 
+// The default entry point for /subsystem:windows. In Crashpad’s own build, this
+// is used by crashpad_handler.exe. It’s also used by crashpad_handler.com when
+// produced by editbin from a copy of crashpad_handler.exe.
 int APIENTRY wWinMain(HINSTANCE, HINSTANCE, wchar_t*, int) {
   return crashpad::ToolSupport::Wmain(__argc, __wargv, HandlerMainAdaptor);
 }
+
+// The default entry point for /subsystem:console. This is not currently used by
+// Crashpad’s own build, but may be used by other builds.
+int wmain(int argc, wchar_t* argv[]) {
+  return crashpad::ToolSupport::Wmain(argc, argv, HandlerMainAdaptor);
+}
+
 #endif  // OS_MACOSX