build: [gn] working on 32bit windows

atom/common/crash_reporter/crash_reporter_win.h

@@ -65,7 +65,9 @@ class CrashReporterWin : public CrashReporter {
   google_breakpad::CustomClientInfo custom_info_;
 
   bool skip_system_crash_handler_ = false;
+#ifdef _WIN64
   bool code_range_registered_ = false;
+#endif
   std::unique_ptr<google_breakpad::ExceptionHandler> breakpad_;
 
   DISALLOW_COPY_AND_ASSIGN(CrashReporterWin);

build/node/BUILD.gn

@@ -27,6 +27,7 @@ action("configure_node") {
     "--prefix=",
     "--config-out-dir=" + rebase_path(target_gen_dir),
     "--no-run-gyp",
+    "--dest-cpu=$target_cpu",
   ]
   if (is_component_build) {
     args += [ "--shared" ]

docs/development/build-instructions-gn.md

@@ -69,6 +69,21 @@ $ ./out/Default/Electron.app/Contents/MacOS/Electron
 $ ./out/Default/electron
 ```
 
+### Cross-compiling
+
+To compile for a platform that isn't the same as the one you're building on,
+set the `target_cpu` GN argument. For example, to compile a windows x86 target
+from an x64 host, specify `target_cpu = "x86"` in `gn args`.
+
+```sh
+$ gn gen out/Default-x86 --args='... target_cpu = "x86"'
+```
+
+Not all combinations of source and target CPU/OS are supported by Chromium.
+Only cross-compiling Windows 32-bit from Windows 64-bit has been tested in
+Electron. If you test other combinations and find them to work, please update
+this document :)
+
 ## Tests
 
 To run the tests, you'll first need to build the test modules against the