Prepare ClearBrowsingDataDialogFragment for browsing data counters.

chrome/browser/android/browsing_data/browsing_data_counter_bridge.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_ANDROID_BROWSING_DATA_BROWSING_DATA_COUNTER_BRIDGE_H_
+#define CHROME_BROWSER_ANDROID_BROWSING_DATA_BROWSING_DATA_COUNTER_BRIDGE_H_
+
+#include "base/android/jni_weak_ref.h"
+#include "base/android/scoped_java_ref.h"
+#include "chrome/browser/browsing_data/browsing_data_counter.h"
+
+class Profile;
+
+// This class is a wrapper for BrowsingDataCounter (C++ backend) to be used by
+// ClearBrowsingDataFragment (Java UI).
+class BrowsingDataCounterBridge {
+ public:
+  BrowsingDataCounterBridge(

[newt (away), 2016/01/12 18:55:26]

Document this. In particular, what are valid values for dataType?

[msramek, 2016/01/13 15:27:53]

Done. Also, renamed to |data_type|, since this is C++ :)

+      JNIEnv* env,
+      const base::android::JavaParamRef<jobject>& obj,
+      jint dataType);
+
+  ~BrowsingDataCounterBridge();
+
+  // Called by the Java counterpart when it is getting garbage collected.
+  void Destroy(JNIEnv* env, const base::android::JavaParamRef<jobject>& obj);
+
+  void Callback(scoped_ptr<BrowsingDataCounter::Result> result);

[newt (away), 2016/01/12 18:55:26]

Should this method be private? Also, Callback is a very vague name; how about
giving this the same name as the corresponding Java method:
OnBrowsingDataCounterFinished()?

[msramek, 2016/01/13 15:27:53]

Done. Renamed to |OnCounterFinished|, as that is the name of the Java method,
and the "browsing data" part is implied by the name of the class. And yes, it
should be private.

+
+  bool valid() { return counter_; }

[newt (away), 2016/01/12 18:55:26]

Where is this method called?

[msramek, 2016/01/13 15:27:53]

Hmm, good catch. I know that I added here to test if a counter is non-NULL, i.e.
if it exists for the given data type, but this actually isn't called anywhere.

If a counter doesn't exist, the constructor returns early, and no callbacks are
ever called. No need for external checks right now.

+
+ private:
+  base::android::ScopedJavaGlobalRef<jobject> jobject_;
+  scoped_ptr<BrowsingDataCounter> counter_;
+
+  DISALLOW_COPY_AND_ASSIGN(BrowsingDataCounterBridge);
+};
+
+bool RegisterBrowsingDataCounterBridge(JNIEnv* env);
+
+#endif // CHROME_BROWSER_ANDROID_BROWSING_DATA_BROWSING_DATA_COUNTER_BRIDGE_H_