Make unit_tests compile in Mac GN

build/secondary/third_party/crashpad/crashpad/client/BUILD.gn

Index: build/secondary/third_party/crashpad/crashpad/client/BUILD.gn
diff --git a/build/secondary/third_party/crashpad/crashpad/client/BUILD.gn b/build/secondary/third_party/crashpad/crashpad/client/BUILD.gn
new file mode 100644
index 0000000000000000000000000000000000000000..5cfadfacd719f64f42b88ff3ab12733e45e231ca
--- /dev/null
+++ b/build/secondary/third_party/crashpad/crashpad/client/BUILD.gn
@@ -0,0 +1,45 @@
+# Copyright 2015 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.
+
+config("client_config") {
+  include_dirs = [ ".." ]
+}
+
+source_set("client") {
+  sources = [
+    "capture_context_mac.S",
+    "capture_context_mac.h",
+    "crash_report_database.cc",
+    "crash_report_database.h",
+    "crash_report_database_mac.mm",
+    "crash_report_database_win.cc",
+    "crashpad_client.h",
+    "crashpad_client_mac.cc",
+    "crashpad_client_win.cc",
+    "crashpad_info.cc",
+    "crashpad_info.h",
+    "prune_crash_reports.cc",
+    "prune_crash_reports.h",
+    "settings.cc",
+    "settings.h",
+    "simple_string_dictionary.cc",
+    "simple_string_dictionary.h",
+    "simulate_crash.h",
+    "simulate_crash_mac.cc",
+    "simulate_crash_mac.h",
+    "simulate_crash_win.h",
+  ]
+
+  public_configs = [ ":client_config" ]
+
+  deps = [
+    "//base",
+    "//third_party/crashpad/crashpad/compat",
+    "//third_party/crashpad/crashpad/util",
+  ]
+
+  if (is_win) {
+    libs = [ "rpcrt4.lib" ]
+  }
+}