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

base/android/jni_android_unittest.cc

+// Copyright (c) 2011 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.
+
+#include "base/android/jni_android.h"
+
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+namespace android {
+
+namespace {
+
+const char kJavaLangObject[] = "java/lang/Object";
+const char kGetClass[] = "getClass";
+const char kToString[] = "toString";
+const char kReturningJavaLangClass[] = "()Ljava/lang/Class;";
+const char kReturningJavaLangString[] = "()Ljava/lang/String;";
+
+const char* g_last_method;
+const char* g_last_jni_signature;
+jmethodID g_last_method_id;
+
+JNINativeInterface g_previous_functions = {0};
+
+jmethodID GetMethodIDWrapper(JNIEnv* env, jclass clazz, const char* method,
+                             const char* jni_signature) {
+  g_last_method = method;
+  g_last_jni_signature = jni_signature;
+  g_last_method_id = g_previous_functions.GetMethodID(env, clazz, method,
+                                                      jni_signature);
+  return g_last_method_id;
+}
+
+}  // namespace
+
+class JNIAndroidTest : public testing::Test {
+ protected:
+  virtual void SetUp() {
+    JNIEnv* env = AttachCurrentThread();
+    g_previous_functions = *env->functions;
+    JNINativeInterface* native_interface =
+        const_cast<JNINativeInterface*>(env->functions);
+    native_interface->GetMethodID = &GetMethodIDWrapper;
+  }
+
+  virtual void TearDown() {
+    JNIEnv* env = AttachCurrentThread();
+    *(const_cast<JNINativeInterface*>(env->functions)) = g_previous_functions;
+  }
+
+  void Reset() {
+    g_last_method = 0;
+    g_last_jni_signature = 0;
+    g_last_method_id = NULL;
+  }
+};
+
+TEST_F(JNIAndroidTest, GetMethodIDFromClassNameCaching) {
+  JNIEnv* env = AttachCurrentThread();
+
+  Reset();
+  jmethodID id1 = GetMethodIDFromClassName(env, kJavaLangObject, kGetClass,
+                                           kReturningJavaLangClass);
+  EXPECT_STREQ(kGetClass, g_last_method);
+  EXPECT_STREQ(kReturningJavaLangClass, g_last_jni_signature);
+  EXPECT_EQ(g_last_method_id, id1);
+
+  Reset();
+  jmethodID id2 = GetMethodIDFromClassName(env, kJavaLangObject, kGetClass,
+                                           kReturningJavaLangClass);
+  EXPECT_STREQ(0, g_last_method);
+  EXPECT_STREQ(0, g_last_jni_signature);
+  EXPECT_EQ(NULL, g_last_method_id);
+  EXPECT_EQ(id1, id2);
+
+  Reset();
+  jmethodID id3 = GetMethodIDFromClassName(env, kJavaLangObject, kToString,
+                                           kReturningJavaLangString);
+  EXPECT_STREQ(kToString, g_last_method);
+  EXPECT_STREQ(kReturningJavaLangString, g_last_jni_signature);
+  EXPECT_EQ(g_last_method_id, id3);
+}
+
+}  // namespace android
+}  // namespace base