bootstrap: Initialize crash reporting (see #3935)

This adds a runtime dependency on chrome_elf.dll and makes all
runtime errors LOG(FATAL) to generate a crash report. Don't wait
for libcef to load before running as the crashpad-handler process.

libcef/browser/crashpad_runner.h

@@ -0,0 +1,22 @@
+// Copyright 2020 The Chromium Embedded Framework Authors.
+// Portions copyright 2014 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.
+
+#ifndef CEF_LIBCEF_BROWSER_CRASHPAD_RUNNER_H_
+#define CEF_LIBCEF_BROWSER_CRASHPAD_RUNNER_H_
+
+#include "base/command_line.h"
+
+namespace crashpad_runner {
+
+// Chrome uses an embedded crashpad handler on Windows only and imports this
+// function via the existing "run_as_crashpad_handler" target defined in
+// components/crash/core/app/BUILD.gn. CEF uses an embedded handler on all
+// platforms so we define the function here instead of using the existing
+// target (because we can't use that target on macOS).
+int RunAsCrashpadHandler(const base::CommandLine& command_line);
+
+}  // namespace crashpad_runner
+
+#endif  // CEF_LIBCEF_BROWSER_CRASHPAD_RUNNER_H_