Add an override flag to enable metrics reporting.

chrome/browser/metrics/chrome_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 CHROME_BROWSER_METRICS_CHROME_METRICS_SERVICE_CLIENT_H_
 #define CHROME_BROWSER_METRICS_CHROME_METRICS_SERVICE_CLIENT_H_
 
 #include <stdint.h>
 
 #include <deque>
@@ skipping 46 matching lines @@
  public:
   ~ChromeMetricsServiceClient() override;
 
   // Factory function.
   static std::unique_ptr<ChromeMetricsServiceClient> Create(
       metrics::MetricsStateManager* state_manager);
 
   // Registers local state prefs used by this class.
   static void RegisterPrefs(PrefRegistrySimple* registry);
 
+  // Checks if the user has forced metrics collection on via the override flag.
+  static bool IsMetricsReportingForceEnabled();
+
   // metrics::MetricsServiceClient:
   metrics::MetricsService* GetMetricsService() override;
   ukm::UkmService* GetUkmService() override;
   void SetMetricsClientId(const std::string& client_id) override;
   int32_t GetProduct() override;
   std::string GetApplicationLocale() override;
   bool GetBrand(std::string* brand_code) override;
   metrics::SystemProfileProto::Channel GetChannel() override;
   std::string GetVersionString() override;
   void OnEnvironmentUpdate(std::string* serialized_environment) override;
@@ skipping 170 matching lines @@
   // Whether this client has already uploaded profiler data during this session.
   // Profiler data is uploaded at most once per session.
   bool has_uploaded_profiler_data_;
 
   base::WeakPtrFactory<ChromeMetricsServiceClient> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ChromeMetricsServiceClient);
 };
 
 #endif  // CHROME_BROWSER_METRICS_CHROME_METRICS_SERVICE_CLIENT_H_