Add generate_jar_jni template

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 107 matching lines @@
       "//content/public/renderer",
       "//ppapi:ppapi_c",
       "//third_party/libusb",
       #"//third_party/WebKit/Source/platform",
       "//third_party/WebKit/Source/wtf",  # TODO(brettw) re-enable for Android.
       "//tools/gn",
 
       # Not tested on Android yet:
       "//webkit/browser:storage",
       "//webkit/child",
-
-      # This stuff all depends on ui/surface which requires some .class jni
-      # generators (ui/gl/gl.gyp:surface_jni_headers).
-      "//ui/gl",
-      "//gpu",
-      "//ui/snapshot",
-      "//ui/surface",
     ]
   }
 }