Add external data use observer

chrome/browser/io_thread.cc

Index: chrome/browser/io_thread.cc
diff --git a/chrome/browser/io_thread.cc b/chrome/browser/io_thread.cc
index 165bf37aaafac32b370109297fbcd70c6021dfa4..7f359cfd738ca12a29047be32337d5160f2737a2 100644
--- a/chrome/browser/io_thread.cc
+++ b/chrome/browser/io_thread.cc
@@ -108,6 +108,7 @@
 
 #if defined(OS_ANDROID)
 #include "base/android/build_info.h"
+#include "chrome/browser/android/datausage/external_data_use_observer_android.h"
 #include "chrome/browser/android/net/external_estimate_provider_android.h"
 #endif
 
@@ -583,6 +584,16 @@ void IOThread::Init() {
       globals_->data_use_aggregator.get(),
       true /* is_data_usage_off_the_record */);
 
+#if defined(OS_ANDROID)
+  scoped_ptr<data_usage::DataUseAggregator::Observer>
+      external_data_use_observer(
+          new chrome::android::ExternalDataUseObserverAndroid(
+              globals_->data_use_aggregator.get()));
+
+  globals_->data_use_aggregator->PassExternalObserver(
+      external_data_use_observer.Pass());
+#endif
+
   // TODO(erikchen): Remove ScopedTracker below once http://crbug.com/466432
   // is fixed.
   tracked_objects::ScopedTracker tracking_profile4(