Add external data use observer

chrome/browser/android/datausage/external_data_use_observer_android.h

+// Copyright 2015 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_DATAUSAGE_EXTERNAL_DATA_USE_OBSERVER_ANDROID_H_
+#define CHROME_BROWSER_ANDROID_DATAUSAGE_EXTERNAL_DATA_USE_OBSERVER_ANDROID_H_
+
+#include <jni.h>
+#include <vector>
+
+#include "base/android/scoped_java_ref.h"
+#include "base/gtest_prod_util.h"
+#include "base/macros.h"
+#include "base/threading/thread_checker.h"
+#include "components/data_usage/core/data_use.h"
+#include "components/data_usage/core/data_use_aggregator.h"
+
+namespace chrome {
+
+namespace android {
+
+// This class defines a data use observer external to Chromium. It creates and
+// owns a Java listener object that listens to data use observations. Native
+// code receives regular expressions from the Java listener. This class also
+// registers as a data use observer with DataUseAggregator, applies the regular
+// expressions to the received observations, and reports the matching data use
+// reports to the Java listener.
+class ExternalDataUseObserverAndroid
+    : public data_usage::DataUseAggregator::Observer {
+ public:
+  explicit ExternalDataUseObserverAndroid(
+      data_usage::DataUseAggregator* data_use_aggregator);
+  ~ExternalDataUseObserverAndroid() override;
+
+ private:
+  FRIEND_TEST_ALL_PREFIXES(ExternalDataUseObserverAndroidTest, SingleRegex);
+  FRIEND_TEST_ALL_PREFIXES(ExternalDataUseObserverAndroidTest, TwoRegex);
+  FRIEND_TEST_ALL_PREFIXES(ExternalDataUseObserverAndroidTest, MultipleRegex);
+
+  // data_usage::DataUseAggregator::Observer implementation:
+  void OnDataUse(
+      const std::vector<data_usage::DataUse>& data_use_sequence) override;
+
+  // Called by Java to register multiple regular expressions. If the url of the
+  // data use request matches any of the regular expression, the observation is
+  // passed to the Java listener.
+  void RegisterURLRegexes(const std::vector<std::string>& url_regexes);
+
+  // Returns true if the |gurl| matches the registered regular expressions.
+  bool Matches(const GURL& gurl) const;
+
+  // Aggregator that sends data use observations. May be nullptr.

[sclittle, 2015/10/09 22:59:28]

Why can this be nullptr?

[tbansal1, 2015/10/12 16:47:36]

Removed.

+  data_usage::DataUseAggregator* data_use_aggregator_;
+
+  // Java listener.
+  base::android::ScopedJavaGlobalRef<jobject> j_external_data_use_observer_;
+
+  // Registered regular expressions.
+  std::vector<std::string> url_regexes_;

[sclittle, 2015/10/09 22:59:28]

Could you pre-compile the RE2 patterns?

[tbansal1, 2015/10/12 16:47:36]

Done.

+
+  base::ThreadChecker thread_checker_;
+
+  DISALLOW_COPY_AND_ASSIGN(ExternalDataUseObserverAndroid);
+};
+
+bool RegisterExternalDataUseObserverAndroid(JNIEnv* env);
+
+}  // namespace android
+
+}  // namespace chrome
+
+#endif  // CHROME_BROWSER_ANDROID_DATAUSAGE_EXTERNAL_DATA_USE_OBSERVER_ANDROID_H_