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..f48d56289a6a6ce76d0ff4254068a5d0d3294fad 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"
@@ -32,6 +33,10 @@ class BlimpBrowserContext : public content::BrowserContext {
   BlimpBrowserContext(bool off_the_record, net::NetLog* net_log);
   ~BlimpBrowserContext() override;
 
+  // These map to BrowserMainParts::Pre/PostMainMessageLoopRun respectively.
+  void Initialize();
+  void Finalize();
+
   // content::BrowserContext implementation.
   std::unique_ptr<content::ZoomLevelDelegate> CreateZoomLevelDelegate(
       const base::FilePath& partition_path) override;
@@ -67,6 +72,11 @@ class BlimpBrowserContext : public content::BrowserContext {
   // allowed on the current thread.
   void InitWhileIOAllowed();
 
+  void InitPrefService();
+
+  // Used by metrics service to persist logs and other information.
+  std::unique_ptr<PrefService> pref_service_;
+
   std::unique_ptr<BlimpResourceContext> resource_context_;
   scoped_refptr<BlimpSystemURLRequestContextGetter> system_context_getter_;
   bool ignore_certificate_errors_;