JNI Zero: Do not dereference pointers for @JniType("vector<T*>")

The automatic dereferencing is desirable in some case, but not in all
cases (e.g. Profile*). We shouldn't do it automatically.

Bug: b/326465150
Change-Id: Iee8c3ddf1eb5c306c6f88556a94aafa93876a706
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5527567
Auto-Submit: Andrew Grieve <agrieve@chromium.org>
Commit-Queue: Andrew Grieve <agrieve@chromium.org>
Reviewed-by: Henrique Nakashima <hnakashima@chromium.org>
Owners-Override: Andrew Grieve <agrieve@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1299450}

base/android/jni_conversions.cc

@@ -28,6 +28,17 @@ BASE_EXPORT ScopedJavaLocalRef<jobject> ToJniType<std::string>(
   return base::android::ConvertUTF8ToJavaString(env, input);
 }
 
+// Enables vector<const std::string*> to avoid copies.
+template <>
+BASE_EXPORT ScopedJavaLocalRef<jobject> ToJniType<const std::string*>(
+    JNIEnv* env,
+    const std::string* const& input) {
+  if (!input) {
+    return nullptr;
+  }
+  return base::android::ConvertUTF8ToJavaString(env, *input);
+}
+
 template <>
 BASE_EXPORT ScopedJavaLocalRef<jobject> ToJniType<const char*>(
     JNIEnv* env,
@@ -50,6 +61,17 @@ BASE_EXPORT ScopedJavaLocalRef<jobject> ToJniType<std::u16string>(
   return base::android::ConvertUTF16ToJavaString(env, input);
 }
 
+// Enables vector<const std::u16string*> to avoid copies.
+template <>
+BASE_EXPORT ScopedJavaLocalRef<jobject> ToJniType<const std::u16string*>(
+    JNIEnv* env,
+    const std::u16string* const& input) {
+  if (!input) {
+    return nullptr;
+  }
+  return base::android::ConvertUTF16ToJavaString(env, *input);
+}
+
 template <>
 BASE_EXPORT ScopedJavaLocalRef<jobject> ToJniType<std::u16string_view>(
     JNIEnv* env,

third_party/jni_zero/jni_zero.h

@@ -759,21 +759,6 @@ struct ConvertArray<ContainerType> {
  private:
   using ElementType = std::remove_const_t<typename ContainerType::value_type>;
 
-  static ScopedJavaLocalRef<jobject> ElementToJniType(
-      JNIEnv* env,
-      const ElementType& element) {
-    if constexpr (std::is_pointer_v<ElementType> &&
-                  !std::is_fundamental_v<std::remove_pointer_t<ElementType>>) {
-      // Dereference object pointers to enable using vector<ContainerType*>
-      // in order to avoid copying objects for the sake of JNI.
-      return jni_zero::ToJniType<
-          std::remove_const_t<std::remove_pointer_t<ElementType>>>(env,
-                                                                   *element);
-    } else {
-      return jni_zero::ToJniType<ElementType>(env, element);
-    }
-  }
-
  public:
   static ContainerType FromJniType(JNIEnv* env,
                                    const JavaRef<jobjectArray>& j_array) {
@@ -822,7 +807,8 @@ struct ConvertArray<ContainerType> {
       if constexpr (std::is_base_of_v<JavaRef<jobject>, ElementType>) {
         env->SetObjectArrayElement(j_array, i, value.obj());
       } else {
-        ScopedJavaLocalRef<jobject> element = ElementToJniType(env, value);
+        ScopedJavaLocalRef<jobject> element =
+            jni_zero::ToJniType<ElementType>(env, value);
         env->SetObjectArrayElement(j_array, i, element.obj());
       }
       ++i;

url/android/gurl_android.cc

@@ -38,6 +38,17 @@ COMPONENT_EXPORT(URL)
 ScopedJavaLocalRef<jobject> ToJniType<GURL>(JNIEnv* env, const GURL& gurl) {
   return url::GURLAndroid::FromNativeGURL(env, gurl);
 }
+
+// Enables vector<const GURL*> to avoid copies.
+template <>
+COMPONENT_EXPORT(URL)
+ScopedJavaLocalRef<jobject> ToJniType<const GURL*>(JNIEnv* env,
+                                                   const GURL* const& gurl) {
+  if (!gurl) {
+    return nullptr;
+  }
+  return url::GURLAndroid::FromNativeGURL(env, *gurl);
+}
 }  // namespace jni_zero
 
 namespace url {