Fix a bug in video_encoder_wrapper where int array was not freed properly.

JNI_COMMIT doesn't actually free the buffer.

From JNI docs:
0: copy back the content and free the elems buffer
JNI_COMMIT: copy back the content but do not free the elems buffer
JNI_ABORT: free the buffer without copying back the possible changes

Also introduces helper methods to help avoid this problem in the
future.

Bug: webrtc:10132
Change-Id: I769df286d3bd186fdf39ee2363e9002f36454509
Reviewed-on: https://webrtc-review.googlesource.com/c/120600
Reviewed-by: Magnus Jedvert <magjed@webrtc.org>
Commit-Queue: Sami Kalliomäki <sakal@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#26529}

sdk/android/native_unittests/java_types_unittest.cc

@@ -30,6 +30,47 @@ TEST(JavaTypesTest, TestJavaToNativeStringMap) {
   };
   EXPECT_EQ(expected, output);
 }
+
+TEST(JavaTypesTest, TestNativeToJavaToNativeIntArray) {
+  JNIEnv* env = AttachCurrentThreadIfNeeded();
+
+  std::vector<int32_t> test_data{1, 20, 300};
+
+  ScopedJavaLocalRef<jintArray> array = NativeToJavaIntArray(env, test_data);
+  EXPECT_EQ(test_data, JavaToNativeIntArray(env, array));
+}
+
+TEST(JavaTypesTest, TestNativeToJavaToNativeByteArray) {
+  JNIEnv* env = AttachCurrentThreadIfNeeded();
+
+  std::vector<int8_t> test_data{1, 20, 30};
+
+  ScopedJavaLocalRef<jbyteArray> array = NativeToJavaByteArray(env, test_data);
+  EXPECT_EQ(test_data, JavaToNativeByteArray(env, array));
+}
+
+TEST(JavaTypesTest, TestNativeToJavaToNativeIntArrayLeakTest) {
+  JNIEnv* env = AttachCurrentThreadIfNeeded();
+
+  std::vector<int32_t> test_data{1, 20, 300};
+
+  for (int i = 0; i < 2000; i++) {
+    ScopedJavaLocalRef<jintArray> array = NativeToJavaIntArray(env, test_data);
+    EXPECT_EQ(test_data, JavaToNativeIntArray(env, array));
+  }
+}
+
+TEST(JavaTypesTest, TestNativeToJavaToNativeByteArrayLeakTest) {
+  JNIEnv* env = AttachCurrentThreadIfNeeded();
+
+  std::vector<int8_t> test_data{1, 20, 30};
+
+  for (int i = 0; i < 2000; i++) {
+    ScopedJavaLocalRef<jbyteArray> array =
+        NativeToJavaByteArray(env, test_data);
+    EXPECT_EQ(test_data, JavaToNativeByteArray(env, array));
+  }
+}
 }  // namespace
 }  // namespace test
 }  // namespace webrtc