Re-land "Add GN build targets for the rest of mojo/public"

mojo/public/java/BUILD.gn

Index: mojo/public/java/BUILD.gn
diff --git a/mojo/public/java/BUILD.gn b/mojo/public/java/BUILD.gn
new file mode 100644
index 0000000000000000000000000000000000000000..8e0a2dc068f884c89cc5a8dd0e886bb27a000cac
--- /dev/null
+++ b/mojo/public/java/BUILD.gn
@@ -0,0 +1,22 @@
+# Copyright 2014 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("java") {
+  java_files = [
+    "src/org/chromium/mojo/system/AsyncWaiter.java",
+    "src/org/chromium/mojo/system/Core.java",
+    "src/org/chromium/mojo/system/DataPipe.java",
+    "src/org/chromium/mojo/system/Flags.java",
+    "src/org/chromium/mojo/system/Handle.java",
+    "src/org/chromium/mojo/system/InvalidHandle.java",
+    "src/org/chromium/mojo/system/MessagePipeHandle.java",
+    "src/org/chromium/mojo/system/MojoException.java",
+    "src/org/chromium/mojo/system/MojoResult.java",
+    "src/org/chromium/mojo/system/Pair.java",
+    "src/org/chromium/mojo/system/SharedBufferHandle.java",
+    "src/org/chromium/mojo/system/UntypedHandle.java",
+  ]
+}