Make class lookup lazy in jni_generator when using lazy method lookup.

base/android/jni_android.h

 // Copyright (c) 2012 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 BASE_ANDROID_JNI_ANDROID_H_
 #define BASE_ANDROID_JNI_ANDROID_H_
 
 #include <jni.h>
 #include <sys/types.h>
 
@@ skipping 35 matching lines @@
 
 // Returns true if the global JVM has been initialized.
 BASE_EXPORT bool IsVMInitialized();
 
 // Initializes the global application context object. The |context| can be any
 // valid reference to the application context. Internally holds a global ref to
 // the context. InitVM and InitApplicationContext maybe called in either order.
 BASE_EXPORT void InitApplicationContext(JNIEnv* env,
                                         const JavaRef<jobject>& context);
 
+// Initializes the global ClassLoader used by the GetClass and LazyGetClass
+// methods. This is needed because JNI will use the base ClassLoader when there
+// is no Java code on the stack. The base ClassLoader doesn't know about any of
+// the application classes and will fail to lookup anything other than system
+// classes.
+BASE_EXPORT void InitReplacementClassLoader(
+    JNIEnv* env,
+    const JavaRef<jobject>& class_loader);
+
 // Gets a global ref to the application context set with
 // InitApplicationContext(). Ownership is retained by the function - the caller
 // must NOT release it.
 const BASE_EXPORT jobject GetApplicationContext();
 
 // Finds the class named |class_name| and returns it.
 // Use this method instead of invoking directly the JNI FindClass method (to
 // prevent leaking local references).
 // This method triggers a fatal assertion if the class could not be found.
 // Use HasClass if you need to check whether the class exists.
 BASE_EXPORT ScopedJavaLocalRef<jclass> GetClass(JNIEnv* env,
                                                 const char* class_name);
 
+// The method will initialize |atomic_class_id| to contain a global ref to the
+// class. And will return that ref on subsequent calls.  It's the caller's
+// responsibility to release the ref when it is no longer needed.
+// The caller is responsible to zero-initialize |atomic_method_id|.
+// It's fine to simultaneously call this on multiple threads referencing the
+// same |atomic_method_id|.
+BASE_EXPORT jclass LazyGetClass(
+    JNIEnv* env,
+    const char* class_name,
+    base::subtle::AtomicWord* atomic_class_id);
+
 // This class is a wrapper for JNIEnv Get(Static)MethodID.
 class BASE_EXPORT MethodID {
  public:
   enum Type {
     TYPE_STATIC,
     TYPE_INSTANCE,
   };
 
   // Returns the method ID for the method with the specified name and signature.
   // This method triggers a fatal assertion if the method could not be found.
@@ skipping 21 matching lines @@
 // and returns true.
 BASE_EXPORT bool ClearException(JNIEnv* env);
 
 // This function will call CHECK() macro if there's any pending exception.
 BASE_EXPORT void CheckException(JNIEnv* env);
 
 }  // namespace android
 }  // namespace base
 
 #endif  // BASE_ANDROID_JNI_ANDROID_H_