[UMA] Include field trial tuples in the UMA upload.

chrome/common/metrics/metrics_log_base.h

 // Copyright (c) 2012 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.
 
 // This file defines a set of user experience metrics data recorded by
 // the MetricsService.  This is the unit of data that is sent to the server.
 
 #ifndef CHROME_COMMON_METRICS_METRICS_LOG_BASE_H_
 #define CHROME_COMMON_METRICS_METRICS_LOG_BASE_H_
 #pragma once
@@ skipping 86 matching lines @@
 
   void set_hardware_class(const std::string& hardware_class) {
     hardware_class_ = hardware_class;
   }
 
  protected:
   class XmlWrapper;
 
   // Returns a string containing the current time.
   // Virtual so that it can be overridden for testing.
+  // TODO(isherman): Remove this method once the XML pipeline is old news.
   virtual std::string GetCurrentTimeString();
   // Helper class that invokes StartElement from constructor, and EndElement
   // from destructor.
   //
   // Use the macro OPEN_ELEMENT_FOR_SCOPE to help avoid usage problems.
   class ScopedElement {
    public:
     ScopedElement(MetricsLogBase* log, const std::string& name) : log_(log) {
       DCHECK(log);
       log->StartElement(name.c_str());
@@ skipping 23 matching lines @@
   // Convenience versions of xmlWriter functions
   void StartElement(const char* name);
   void EndElement();
   void WriteAttribute(const std::string& name, const std::string& value);
   void WriteIntAttribute(const std::string& name, int value);
   void WriteInt64Attribute(const std::string& name, int64 value);
 
   // Write the attributes that are common to every metrics event type.
   void WriteCommonEventAttributes();
 
+  bool locked() const { return locked_; }
+
+  metrics::ChromeUserMetricsExtension* uma_proto() { return &uma_proto_; }

[jar (doing other things), 2012/03/01 05:32:42]

This is a scary interface. Why do other folks need to know where you keep your
slot?

[Ilya Sherman, 2012/03/01 06:41:50]

This method has protected visibility -- only MetricsLog gets to peek into this
implementation detail.  (Well, ok, testing classes theoretically could peek in
as well, but I don't see a clean way to avoid that.)

+  const metrics::ChromeUserMetricsExtension& uma_proto() const {

[jar (doing other things), 2012/03/01 05:32:42]

This seems a bit confusing to me, as you have overloaded based on the const-ness
of the instance, but then returned different  values.  I'd expect this will be
confusing (surprising?) when used, as the const-ness is often not locally
apparent at the call site.  i.e., sometimes you could say:
uma_proto().blah
other times:
uma_proto()->blah

[Ilya Sherman, 2012/03/01 06:41:50]

Fair enough, updated this to be a pointer as well.

+    return uma_proto_;
+  }
+
+  // TODO(isherman): Remove this once the XML pipeline is outta here.
+  int num_events_;  // the number of events recorded in this log
+
+ private:
   base::Time start_time_;
   base::Time end_time_;
 
   std::string client_id_;
   std::string session_id_;
   std::string hardware_class_;
 
   // locked_ is true when record has been packed up for sending, and should
   // no longer be written to.  It is only used for sanity checking and is
   // not a real lock.
   bool locked_;
 
   // Isolated to limit the dependency on the XML library for our consumers.
   XmlWrapper* xml_wrapper_;
 
-  int num_events_;  // the number of events recorded in this log
-
   // Stores the protocol buffer representation for this log.
   metrics::ChromeUserMetricsExtension uma_proto_;
 
- private:
   DISALLOW_COPY_AND_ASSIGN(MetricsLogBase);
 };
 
 #endif  // CHROME_COMMON_METRICS_METRICS_LOG_BASE_H_