Get headless_shell building on Windows.

headless/lib/headless_content_main_delegate.cc

Index: headless/lib/headless_content_main_delegate.cc
diff --git a/headless/lib/headless_content_main_delegate.cc b/headless/lib/headless_content_main_delegate.cc
index 72df5a29a65a3adaa86b5a24e36bdc028f8dce92..695821c779ec568b4014fdec900a60ec56babb7d 100644
--- a/headless/lib/headless_content_main_delegate.cc
+++ b/headless/lib/headless_content_main_delegate.cc
@@ -211,7 +211,9 @@ void HeadlessContentMainDelegate::ZygoteForked() {
   // Unconditionally try to turn on crash reporting since we do not have access
   // to the latest browser options at this point when testing. Breakpad will
   // bail out gracefully if the browser process hasn't enabled crash reporting.
+#if defined(HEADLESS_USE_BREAKPAD)
   breakpad::InitCrashReporter(process_type);
+#endif
 }
 #endif