Upstream: Add WebAPK's client library.

chrome/android/webapk/libs/client/BUILD.gn

Index: chrome/android/webapk/libs/client/BUILD.gn
diff --git a/chrome/android/webapk/libs/client/BUILD.gn b/chrome/android/webapk/libs/client/BUILD.gn
new file mode 100644
index 0000000000000000000000000000000000000000..1f3bfb29251fabd3604c12431e87e55f4e226ff9
--- /dev/null
+++ b/chrome/android/webapk/libs/client/BUILD.gn
@@ -0,0 +1,21 @@
+# Copyright 2016 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.
+
+import("//build/config/android/rules.gni")
+
+android_library("client") {
+  java_files = [ "src/org/chromium/webapk/lib/client/WebApkValidator.java" ]
+  deps = [
+    "//chrome/android/webapk/libs/common",
+  ]
+}
+
+junit_binary("webapk_client_junit_tests") {
+  java_files =
+      [ "junit/src/org/chromium/webapk/lib/client/WebApkValidatorTest.java" ]
+  deps = [
+    ":client",
+    "//base:base_junit_test_support",
+  ]
+}