predictors: Make the resource_prefetch_predictor accessible from Java.

chrome/browser/predictors/resource_prefetch_predictor_android.h

+// Copyright 2016 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 CHROME_BROWSER_PREDICTORS_RESOURCE_PREFETCH_PREDICTOR_ANDROID_H_
+#define CHROME_BROWSER_PREDICTORS_RESOURCE_PREFETCH_PREDICTOR_ANDROID_H_
+
+#include <jni.h>
+
+#include "base/macros.h"
+
+namespace base {
+namespace android {
+template <typename T>
+class JavaParamRef;
+}  // namespace android
+}  // namespace base
+
+namespace predictors {
+
+class ResourcePrefetchPredictor;
+
+class ResourcePrefetchPredictorAndroid {
+ public:
+  // See ResourcePrefetchPredictor::StartPrefetching().
+  void StartPrefetching(JNIEnv* env,
+                        const base::android::JavaParamRef<jobject>& jcaller,
+                        const base::android::JavaParamRef<jstring>& j_url);
+  // See ResourcePrefetchPredictor::StopPrefetching().
+  void StopPrefetching(JNIEnv* env,
+                       const base::android::JavaParamRef<jobject>& jcaller,
+                       const base::android::JavaParamRef<jstring>& j_url);
+
+  // Returns a pointer to a new instance of |ResourePrefetchPredictorAndroid|,
+  // for a given profile.
+  static jlong GetForProfile(JNIEnv* env, jclass clazz, jobject j_profile);
+  static bool Register(JNIEnv* env);
+
+ private:
+  explicit ResourcePrefetchPredictorAndroid(
+      ResourcePrefetchPredictor* predictor);
+
+  ResourcePrefetchPredictor* predictor_;

[pasko, 2016/09/27 16:54:31]

What if ResourcePrefetchPredictor is destroyed? Should this be a weakptr
instead?

[Benoit L, 2016/09/28 12:15:25]

Changed to have the object hold a pointer to the profile, not to the predictor.
In practice this should not have much impact, as the predictor doesn't get
destroyed, but it's cleaner this way.

As for why the native profile pointer will live, that's because the native
object is accessed through a map keyed by Profile on the android side.

+
+  DISALLOW_COPY_AND_ASSIGN(ResourcePrefetchPredictorAndroid);
+};
+
+}  // namespace predictors
+
+#endif  // CHROME_BROWSER_PREDICTORS_RESOURCE_PREFETCH_PREDICTOR_ANDROID_H_