Moves NativeViewportApplicationLoader into own files

And gets gn check working

BUG=none
TEST=none
R=qsr@chromium.org

Review URL: https://codereview.chromium.org/810803003
diff --git a/shell/BUILD.gn b/shell/BUILD.gn
index c9856e0..4506cc2 100644
--- a/shell/BUILD.gn
+++ b/shell/BUILD.gn
@@ -68,6 +68,8 @@
 
       deps += [
         ":jni_headers",
+        "//mojo/application_manager:application_manager",
+        "//services/native_viewport:lib",
         "//ui/gl",
       ]
     }
@@ -194,6 +196,8 @@
       "android/android_handler.h",
       "android/android_handler_loader.cc",
       "android/android_handler_loader.h",
+      "android/native_viewport_application_loader.cc",
+      "android/native_viewport_application_loader.h",
       "android/ui_application_loader_android.cc",
       "android/ui_application_loader_android.h",
     ]
@@ -254,6 +258,10 @@
     sources = [
       "android/run_android_application_function.h",
     ]
+
+    deps = [
+      "//base",
+    ]
   }
 
   android_library("java") {