GPU-CTS Program

Add new application, called GPU-CTS (GPU Compatibility Test Suite),
which executes skia gms against OpenGL and Vulkan backends.  Makes use
of googletest library for consistancy with Android CTS programs.

Add googletest to DEPS

gm_knowledge.h header as a stub for future work on validating gm output.

gm_runner can be re-used in other programs.  Talks to Skia and GM with a
simple API.

gpuctx executable wraps gm_runner and googletest together.

Change-Id: Ie7350b22164fa73e44121c39b0f36da4038a700b
Reviewed-on: https://skia-review.googlesource.com/56601
Reviewed-by: Hal Canary <halcanary@google.com>
Commit-Queue: Hal Canary <halcanary@google.com>
diff --git a/third_party/googletest/BUILD.gn b/third_party/googletest/BUILD.gn
new file mode 100644
index 0000000..518360b
--- /dev/null
+++ b/third_party/googletest/BUILD.gn
@@ -0,0 +1,16 @@
+# Copyright 2017 Google Inc.
+#
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import("../third_party.gni")
+
+if (!is_win) {
+  third_party("googletest") {
+    public_include_dirs = [ "../externals/googletest/googletest/include" ]
+    include_dirs = [ "../externals/googletest/googletest" ]
+    sources = [
+      "../externals/googletest/googletest/src/gtest-all.cc",
+    ]
+  }
+}