Histograms - Support histograms for Plugins, GPU

base/metrics/histogram_sender.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.

[jam, 2012/05/31 16:37:04]

why move this file to base? base shouldn't know anything about multi-process,
and you mention it here in a number of places.

why does this need to be derived from in code in chrome and content? 

perhaps it's quicker if we chat about this in person?

 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef CHROME_COMMON_METRICS_HISTOGRAM_SENDER_H_
-#define CHROME_COMMON_METRICS_HISTOGRAM_SENDER_H_
+#ifndef BASE_METRICS_HISTOGRAM_SENDER_H_
+#define BASE_METRICS_HISTOGRAM_SENDER_H_
 #pragma once
 
 #include <map>
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/metrics/histogram.h"
 
+namespace base {
+
 // HistogramSender handles the logistics of gathering up available histograms
 // for transmission (such as from renderer to browser, or from browser to UMA
 // upload).  It has several pure virtual functions that are replaced in
 // derived classes to allow the exact lower level transmission mechanism,
 // or error report mechanism, to be replaced.  Since histograms can sit in
 // memory for an extended period of time, and are vulnerable to memory
 // corruption, this class also validates as much rendundancy as it can before
 // calling for the marginal change (a.k.a., delta) in a histogram to be sent
 // onward.
-class HistogramSender {
+class BASE_EXPORT HistogramSender {
+ public:
+  // Send the histogram data from renderer or child processes.
+  virtual void SendHistograms(int sequence_number) = 0;
+
  protected:
   HistogramSender();
   virtual ~HistogramSender();
 
   // Snapshot all histograms, and transmit the delta.
   // The arguments allow a derived class to select only a subset for
   // transmission, or to set a flag in each transmitted histogram.
   void TransmitAllHistograms(base::Histogram::Flags flags_to_set,
                              bool send_only_uma);
 
@@ skipping 21 matching lines @@
   // For histograms, record what we've already transmitted (as a sample for each
   // histogram) so that we can send only the delta with the next log.
   LoggedSampleMap logged_samples_;
 
   // List of histograms found corrupt to be corrupt, and their problems.
   scoped_ptr<ProblemMap> inconsistencies_;
 
   DISALLOW_COPY_AND_ASSIGN(HistogramSender);
 };
 
-#endif  // CHROME_COMMON_METRICS_HISTOGRAM_SENDER_H_
+}  // namespace base
+
+#endif  // BASE_METRICS_HISTOGRAM_SENDER_H_