Don't use Singleton to cache JNI method IDs in Java Bridge

base/android/jni_android.h

Index: base/android/jni_android.h
diff --git a/base/android/jni_android.h b/base/android/jni_android.h
index 462173f85d38cf48b62e466ebeb97e1b0a6ea006..25e868500eefe963e268ca3c45b19a1fb761061c 100644
--- a/base/android/jni_android.h
+++ b/base/android/jni_android.h
@@ -30,19 +30,13 @@ void InitApplicationContext(jobject context);
 // Returns the application context assigned by InitApplicationContext().
 jobject GetApplicationContext();
 
-// Wraps a method ID.
-class MethodID {
- public:
-  jmethodID id() { return id_; }
- protected:
-  // Gets the method ID from the class name. Clears the pending Java exception
-  // and returns NULL if the method is not found. Note that GetMethodID() below
-  // avoids a class lookup, so should be used in preference when possible.
-  MethodID(JNIEnv* env, const char* class_name, const char* method,
-           const char* jni_signature);
- private:
-  jmethodID id_;
-};
+// Gets the method ID from the class name. Clears the pending Java exception
+// and returns NULL if the method is not found. Note that GetMethodID() below
+// avoids a class lookup, so should be used in preference when possible.
+jmethodID GetMethodIDFromClassName(JNIEnv* env,

[M-A Ruel, 2011/12/01 14:36:03]

I'm taking issue about the design now. Here's the point I'm noting here:

- While the |env| argument is necessary, it's guaranteed to be a constant value
for the caller. In fact, it adds burdens to the caller without any benefit. I'd
prefer this layer to hide this fact.
- You leave value caching to the client. But that will inevitably result in
multiple near implementations in each components calling it. Assuming the return
values are guaranteed to be constant (?), then it'd be preferable to have the
caching transparent here.

+                                   const char* class_name,
+                                   const char* method,
+                                   const char* jni_signature);
 
 // Get the method ID for a method. Will clear the pending Java
 // exception and return 0 if the method is not found.