Add external data use observer

chrome/browser/android/datausage/external_data_use_observer_android.cc

+// 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.
+
+#include "chrome/browser/android/datausage/external_data_use_observer_android.h"
+
+#include "base/android/jni_string.h"
+#include "jni/ExternalDataUseObserverAndroid_jni.h"
+#include "third_party/re2/re2/re2.h"
+#include "url/gurl.h"
+
+using base::android::ConvertUTF8ToJavaString;
+
+namespace chrome {
+
+namespace android {
+
+ExternalDataUseObserverAndroid::ExternalDataUseObserverAndroid(
+    data_usage::DataUseAggregator* data_use_aggregator)
+    : data_use_aggregator_(data_use_aggregator) {
+  DCHECK(data_use_aggregator_);
+
+  JNIEnv* env = base::android::AttachCurrentThread();
+  DCHECK(j_external_data_use_observer_.is_null());
+  j_external_data_use_observer_.Reset(
+      Java_ExternalDataUseObserverAndroid_create(
+          env, base::android::GetApplicationContext(),
+          reinterpret_cast<intptr_t>(this)));
+  DCHECK(!j_external_data_use_observer_.is_null());
+}
+
+ExternalDataUseObserverAndroid::~ExternalDataUseObserverAndroid() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+
+  if (url_patterns_.size() > 0)
+    data_use_aggregator_->RemoveObserver(this);
+}
+
+bool ExternalDataUseObserverAndroid::Matches(const GURL& gurl) const {
+  if (!gurl.is_valid() || gurl.is_empty())
+    return false;
+
+  const std::string& gurl_spec = gurl.spec();
+
+  for (size_t i = 0; i < url_patterns_.size(); ++i) {
+    if (re2::RE2::FullMatch(gurl_spec, *(url_patterns_.at(i))))
+      return true;
+  }
+
+  return false;
+}
+
+void ExternalDataUseObserverAndroid::OnDataUse(
+    const std::vector<data_usage::DataUse>& data_use_sequence) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(!j_external_data_use_observer_.is_null());
+
+  JNIEnv* env = base::android::AttachCurrentThread();
+
+  for (const auto& data_use : data_use_sequence) {
+    if (!Matches(data_use.url))
+      continue;
+
+    // TODO(tbansal): Use buffering to avoid frequent JNI calls.
+    std::string tag = "";  // data_use.tab_id;
+    int64_t bytes_downloaded = data_use.rx_bytes;
+    int64_t bytes_uploaded = data_use.tx_bytes;
+    Java_ExternalDataUseObserverAndroid_onDataUse(
+        env, j_external_data_use_observer_.obj(),
+        ConvertUTF8ToJavaString(env, tag).obj(), bytes_downloaded,
+        bytes_uploaded);
+  }
+}
+
+void ExternalDataUseObserverAndroid::RegisterURLRegexes(
+    const std::vector<std::string>& url_regexes) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+
+  bool registered_as_observer = url_patterns_.size() > 0;
+  if (!registered_as_observer && url_regexes.size() > 0) {
+    registered_as_observer = true;
+    data_use_aggregator_->AddObserver(this);
+  }
+
+  url_patterns_.clear();
+
+  for (const std::string& url_regex : url_regexes) {
+    if (url_regex.empty())
+      continue;
+    re2::RE2::Options options(re2::RE2::DefaultOptions);
+    options.set_case_sensitive(false);

[sclittle, 2015/10/12 20:10:15]

nit: Does it have to be case insensitive? I think URL hostnames are
case-insensitive, but other stuff in the URL is not (e.g. base64-encoded URL
parameters?). For example, https://www.google.com/search?q=chromium vs.
https://www.google.com/search?q=CHROMIUM.

[tbansal1, 2015/10/12 22:39:14]

yes, right now the regex support case insensitive matching only.
In case, we need to support, case sensitive matching, we can
add JNI calls where the external observer tells us if the supplied regex 
should be considered as case sensitive or not.

+    scoped_ptr<re2::RE2> pattern(new re2::RE2(url_regex, options));

[sclittle, 2015/10/12 20:10:15]

What if the pattern is an invalid regex?

[tbansal1, 2015/10/12 22:39:14]

Done.

+    url_patterns_.push_back(pattern.Pass());
+  }
+
+  // Unregister as an observer if no regular expressions were received.
+  if (url_patterns_.size() == 0 && registered_as_observer)
+    data_use_aggregator_->RemoveObserver(this);
+}
+
+bool RegisterExternalDataUseObserverAndroid(JNIEnv* env) {
+  return RegisterNativesImpl(env);
+}
+
+}  // namespace android
+
+}  // namespace chrome