Make MetricsService upload logs through an interface.

components/metrics/metrics_service_client.h

Index: components/metrics/metrics_service_client.h
===================================================================
--- components/metrics/metrics_service_client.h	(revision 274045)
+++ components/metrics/metrics_service_client.h	(working copy)
@@ -9,10 +9,13 @@
 
 #include "base/basictypes.h"
 #include "base/callback_forward.h"
+#include "base/memory/scoped_ptr.h"
 #include "components/metrics/proto/system_profile.pb.h"
 
 namespace metrics {
 
+class MetricsLogUploader;
+
 // An abstraction of operations that depend on the embedder's (e.g. Chrome)
 // environment.
 class MetricsServiceClient {
@@ -50,6 +53,13 @@
   // extra histograms that will go in that log. Asynchronous API - the client
   // implementation should call |done_callback| when complete.
   virtual void CollectFinalMetrics(const base::Closure& done_callback) = 0;
+
+  // Creates a MetricsLogUploader with the specified parameters (see comments on
+  // MetricsLogUploader for details).
+  virtual scoped_ptr<MetricsLogUploader> CreateUploader(
+      const std::string& server_url,
+      const std::string& mime_type,
+      const base::Callback<void(int)>& on_upload_complete) = 0;
 };
 
 }  // namespace metrics