Android: cleanup jni_android to minimize external dependencies.

content/browser/renderer_host/java/jni_helper.h

+// Copyright 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.
+
+#ifndef CONTENT_BROWSER_RENDERER_HOST_JAVA_JNI_HELPER_H_
+#define CONTENT_BROWSER_RENDERER_HOST_JAVA_JNI_HELPER_H_
+
+#include <jni.h>
+
+#include "content/common/content_export.h"
+
+namespace content {
+
+// Gets the method ID from the class name. Clears the pending Java exception
+// and returns NULL if the method is not found. Caches results.
+// Strings passed to this function are held in the cache and MUST remain valid
+// beyond the duration of all future calls to this function, across all
+// threads. In practice, this means that the function should only be used with
+// string constants.
+CONTENT_EXPORT jmethodID GetMethodIDFromClassName(JNIEnv* env,
+                                                  const char* class_name,
+                                                  const char* method,
+                                                  const char* jni_signature);
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_RENDERER_HOST_JAVA_JNI_HELPER_H_