Add generate_jar_jni template

ui/snapshot/BUILD.gn

 # 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/ui.gni")
 
 component("snapshot") {
   sources = [
     "snapshot.h",
     "snapshot_android.cc",
@@ skipping 27 matching lines @@
       "snapshot_async.cc",
       "snapshot_async.h",
     ]
   }
 
   if (use_aura) {
     deps += [
       #"//ui/aura",  TODO(GYP)
       "//ui/compositor",
     ]
+  } else {
+    sources -= [

[cjhopman, 2014/06/04 23:10:12]

I don't know that this is how we actually want to filter aura stuff...

gyp uses a sources filter for it, but it didn't seem like we had any of those
for non-OS concepts (and I, personally, really don't like the magic that is
sources filters).

[tfarina, 2014/06/05 02:12:27]

From what I understood from Brett's reply, that is how we want to do. So we,
that looks right.

For reference, Brett's reply is here:
https://codereview.chromium.org/305993002/diff/160001/ui/base/BUILD.gn#oldcod...

[brettw, 2014/06/05 02:38:15]

Yeah, this is what I have been doing.

+      "snapshot_aura.cc"
+    ]
   }
 }
 
 # TODO(GYP) enable this when all targets are converted and it links
 #test("snapshot_unittests") {
 #  sources = [
 #    "snapshot_aura_unittest.cc",
 #    "snapshot_mac_unittest.mm",
 #    "test/run_all_unittests.cc",
 #  ]
@@ skipping 24 matching lines @@
   source_set("test_support") {
     sources = [
       "test/snapshot_desktop.h",
       "test/snapshot_desktop_win.cc",
     ]
     deps = [
       ":snapshot",
     ]
   }
 }