predictors: Make the resource_prefetch_predictor accessible from Java.

chrome/browser/predictors/resource_prefetch_predictor_android.cc

+// 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.
+
+#include "chrome/browser/predictors/resource_prefetch_predictor_android.h"
+
+#include "base/android/jni_android.h"
+#include "base/android/jni_string.h"
+#include "chrome/browser/predictors/resource_prefetch_predictor.h"
+#include "chrome/browser/predictors/resource_prefetch_predictor_factory.h"
+#include "chrome/browser/profiles/profile.h"
+#include "chrome/browser/profiles/profile_android.h"
+#include "jni/ResourcePrefetchPredictor_jni.h"
+
+using base::android::JavaParamRef;
+using base::android::ScopedJavaLocalRef;
+
+namespace predictors {
+
+void ResourcePrefetchPredictorAndroid::StartPrefetching(
+    JNIEnv* env,
+    const base::android::JavaParamRef<jobject>& jcaller,
+    const JavaParamRef<jstring>& j_url) {
+  ResourcePrefetchPredictor* predictor =
+      ResourcePrefetchPredictorFactory::GetInstance()->GetForProfile(profile_);
+  if (!predictor)
+    return;
+  GURL url = GURL(base::android::ConvertJavaStringToUTF16(env, j_url));
+  predictor->StartPrefetching(url);
+}
+
+void ResourcePrefetchPredictorAndroid::StopPrefetching(
+    JNIEnv* env,
+    const base::android::JavaParamRef<jobject>& jcaller,
+    const JavaParamRef<jstring>& j_url) {
+  ResourcePrefetchPredictor* predictor =
+      ResourcePrefetchPredictorFactory::GetInstance()->GetForProfile(profile_);
+  if (!predictor)
+    return;
+  GURL url = GURL(base::android::ConvertJavaStringToUTF16(env, j_url));
+  predictor->StopPrefetching(url);
+}
+
+// static
+jlong ResourcePrefetchPredictorAndroid::GetForProfile(JNIEnv* env,
+                                                      jclass clazz,
+                                                      jobject j_profile) {
+  Profile* profile = ProfileAndroid::FromProfileAndroid(j_profile);

[gone, 2016/09/28 18:18:15]

FromProfileAndroid can return null.

[Benoit L, 2016/10/03 09:42:05]

The resulting profile is used to call
ResourcePrefetchPredictorFactory::GetForProfile(). It returns nullptr if the
profile is nullptr, and there are checks in Start/StopPrefetching() that return
in this case. So I don't think there is an issue here, the question being more
to the effect of whether we want to make the NULL check in the native or Java
code.

I'm not sure what's best here. wdyt?

[gone, 2016/10/03 21:30:32]

If that and the ResourcePretchPredictorAndroid that you're constructing here are
accounted for then I guess you're fine.  It's deleted at some point, right?

+  ResourcePrefetchPredictorAndroid* predictor_android =
+      new ResourcePrefetchPredictorAndroid(profile);
+  return static_cast<jlong>(reinterpret_cast<intptr_t>(predictor_android));
+}
+
+// static
+bool ResourcePrefetchPredictorAndroid::Register(JNIEnv* env) {
+  return RegisterNativesImpl(env);
+}
+
+static jlong GetResourcePrefetchPredictorForProfile(
+    JNIEnv* env,
+    const JavaParamRef<jclass>& clazz,
+    const JavaParamRef<jobject>& j_profile) {
+  return ResourcePrefetchPredictorAndroid::GetForProfile(env, clazz.obj(),
+                                                         j_profile.obj());
+}
+
+ResourcePrefetchPredictorAndroid::ResourcePrefetchPredictorAndroid(
+    Profile* profile)
+    : profile_(profile) {}
+
+}  // namespace predictors