Flush UKM metrics when backgrounded on Android and iOS.

components/ukm/ukm_service.h

 // Copyright 2017 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 COMPONENTS_UKM_UKM_SERVICE_H_
 #define COMPONENTS_UKM_UKM_SERVICE_H_
 
 #include <stddef.h>
 #include <memory>
 #include <vector>
@@ skipping 47 matching lines @@
 
   // Enables/disables recording control if data is allowed to be collected.
   void EnableRecording();
   void DisableRecording();
 
   // Enables/disables transmission of accumulated logs. Logs that have already
   // been created will remain persisted to disk.
   void EnableReporting();
   void DisableReporting();
 
+#if defined(OS_ANDROID) || defined(OS_IOS)
+  void OnAppEnterBackground();
+  void OnAppEnterForeground();
+#endif
+
   // Records any collected data into logs, and writes to disk.
   void Flush();
 
   // Deletes any unsent local data.
   void Purge();
 
   // Resets the client id stored in prefs.
   void ResetClientId();
 
   // Registers the specified |provider| to provide additional metrics into the
@@ skipping 98 matching lines @@
   // Weak pointers factory used to post task on different threads. All weak
   // pointers managed by this factory have the same lifetime as UkmService.
   base::WeakPtrFactory<UkmService> self_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(UkmService);
 };
 
 }  // namespace ukm
 
 #endif  // COMPONENTS_UKM_UKM_SERVICE_H_