Create and integrate a metrics service client into Blimp engine.

blimp/engine/common/blimp_browser_context.h

Index: blimp/engine/common/blimp_browser_context.h
diff --git a/blimp/engine/common/blimp_browser_context.h b/blimp/engine/common/blimp_browser_context.h
index e02f8316a035d7c664a56e02dd1ce6a5dabf55e4..c05fcaa3e19d7fabff0f63bc38783e724fd97634 100644
--- a/blimp/engine/common/blimp_browser_context.h
+++ b/blimp/engine/common/blimp_browser_context.h
@@ -9,6 +9,7 @@
 
 #include "base/files/file_path.h"
 #include "base/macros.h"
+#include "blimp/engine/app/blimp_metrics_service_client.h"
 #include "blimp/engine/app/blimp_system_url_request_context_getter.h"
 #include "blimp/engine/app/blimp_url_request_context_getter.h"
 #include "content/public/browser/browser_context.h"
@@ -62,11 +63,23 @@ class BlimpBrowserContext : public content::BrowserContext {
   // uploads).
   net::URLRequestContextGetter* GetSystemRequestContextGetter();
 
+  PrefService* GetPrefService() { return pref_service_.get(); }
+
  private:
   // Performs initialization of the BlimpBrowserContext while IO is still
   // allowed on the current thread.
   void InitWhileIOAllowed();
 
+  // Helper function for PrefService initialization.
+  void InitPrefService();
+
+  // Used in metrics initialization to get a PrefService to store logs
+  // temporarily. Must stay alive for lifetime of metrics_service_client_.
+  std::unique_ptr<PrefService> pref_service_;
+
+  // Used for metrics recording and reporting.
+  std::unique_ptr<BlimpMetricsServiceClient> metrics_service_client_;
+
   std::unique_ptr<BlimpResourceContext> resource_context_;
   scoped_refptr<BlimpSystemURLRequestContextGetter> system_context_getter_;
   bool ignore_certificate_errors_;