GN: Get //chrome/* mostly working on android

components/gcm_driver/BUILD.gn

Index: components/gcm_driver/BUILD.gn
diff --git a/components/gcm_driver/BUILD.gn b/components/gcm_driver/BUILD.gn
index 45dd2a26fe7103098dc56a4f92d6107a71dac2aa..a446c9f926ae452de81a600a3f2ac27301cd18ee 100644
--- a/components/gcm_driver/BUILD.gn
+++ b/components/gcm_driver/BUILD.gn
@@ -2,6 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+# GYP version: components/gcm_driver.gypi:gcm_driver
 static_library("gcm_driver") {
   sources = [
     "android/component_jni_registrar.cc",
@@ -100,4 +101,14 @@ static_library("test_support") {
   }
 }
 
-#TODO(GYP) gcm_driver_java gcm_driver_jni_headers
+if (is_android) {
+  import("//build/config/android/rules.gni")
+
+  # GYP version: components/gcm_driver.gypi:gcm_driver_jni_headers
+  generate_jni("jni_headers") {
+    sources = [
+      "android/java/src/org/chromium/components/gcm_driver/GCMDriver.java",
+    ]
+    jni_package = "components/gcm_driver"
+  }
+}