Move MetricsService final log collection tasks to client.

components/metrics/metrics_service_client.h

 // Copyright 2014 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_METRICS_METRICS_SERVICE_CLIENT_H_
 #define COMPONENTS_METRICS_METRICS_SERVICE_CLIENT_H_
 
 #include <string>
 
 #include "base/basictypes.h"
+#include "base/callback_forward.h"
 #include "components/metrics/proto/system_profile.pb.h"
 
 namespace metrics {
 
 // An abstraction of operations that depend on the embedder's (e.g. Chrome)
 // environment.
 class MetricsServiceClient {
  public:
   virtual ~MetricsServiceClient() {}
 
   // Register the client id with other services (e.g. crash reporting), called
   // when metrics recording gets enabled.
   virtual void SetClientID(const std::string& client_id) = 0;
 
   // Whether there's an "off the record" (aka "Incognito") session active.
   virtual bool IsOffTheRecordSessionActive() = 0;
 
   // Returns the current application locale (e.g. "en-US").
   virtual std::string GetApplicationLocale() = 0;
 
   // Retrieves the brand code string associated with the install, returning
   // false if no brand code is available.
   virtual bool GetBrand(std::string* brand_code) = 0;
 
   // Returns the release channel (e.g. stable, beta, etc) of the application.
   virtual SystemProfileProto::Channel GetChannel() = 0;
 
   // Returns the version of the application as a string.
   virtual std::string GetVersionString() = 0;
+
+  // Called prior to a metrics log being closed, allowing the client to collect
+  // extra histograms that will go in that log. Asynchronous API - the client
+  // implementation should call |done_callback| when complete.
+  virtual void OnFinalLogCollection(const base::Closure& done_callback) = 0;
 };
 
 }  // namespace metrics
 
 #endif  // COMPONENTS_METRICS_METRICS_SERVICE_CLIENT_H_