Add automated VR latency tester

BUILD.gn

 # Copyright (c) 2013 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.
 
 # This is the root build file for GN. GN will start processing by loading this
 # file, and recursively load all dependencies until all dependencies are either
 # resolved or known not to exist (which will cause the build to fail). So if
 # you add a new build file, there must be some path of dependencies from this
 # file to your new one or GN won't know about it.
 
@@ skipping 678 matching lines @@
     # This dependency here only exists to allow GN to discover the
     # fuzzer_test target there.
     deps += [ "//chrome/browser/media:cast_remoting_connector_fuzzer" ]
   }
 
   if (enable_nacl) {
     deps += [ "//native_client_sdk/src:nacl_core_sdk" ]
   }
 
   if (is_android) {
-    deps += [ "//build/android/gyp/test:hello_world" ]
+    deps += [
+      "//build/android/gyp/test:hello_world",
+      "//chrome/test/vr/automated_motopho_latency:automated_motopho_latency_test",

[Lei Lei, 2017/04/07 21:36:34]

Why do you add automated_motopho_latency_test target to gn_all target?

I think we can compile automated_motopho_latency_test directly.

[bsheedy, 2017/04/07 23:24:51]

From the top of the file:
"So if you add a new build file, there must be some path of dependencies from
this file to the new one or GN won't know about it."

There might be a better way of meeting this requirement, but there needs to be
some path from //BUILD.gn to
//chrome/test/vr/automated_motopho_latency/BUILD.gn. I considered just making
the test a part of //chrome/android's BUILD.gn, but since this should be
applicable to desktop as well in the future, this seemed like a better approach.

+    ]
   }
 
   if (is_linux && use_ozone) {
     deps += [
       "//headless",
       "//headless:headless_tests",
     ]
   }
 
   if (!is_ios) {
@@ skipping 379 matching lines @@
   assert(target_name != "")  # Mark as used.
   sources = invoker.actual_sources
   assert(
       sources == invoker.actual_sources,
       "Do not use a platform name in your output directory (found \"$root_build_dir\"). http://crbug.com/548283")
 }
 
 assert_valid_out_dir("_unused") {
   actual_sources = [ "$root_build_dir/foo" ]
 }