Send compressed histograms with system logs when sending feedback.

base/metrics/statistics_recorder.cc

 // 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.
 
 #include "base/metrics/statistics_recorder.h"
 
 #include "base/at_exit.h"
 #include "base/debug/leak_annotations.h"
+#include "base/json/string_escape.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/metrics/histogram.h"
 #include "base/strings/stringprintf.h"
 #include "base/synchronization/lock.h"
+#include "base/values.h"
 
 using std::list;
 using std::string;
 
 namespace {
 // Initialize histogram statistics gathering system.
 base::LazyInstance<base::StatisticsRecorder>::Leaky g_statistics_recorder_ =
     LAZY_INSTANCE_INITIALIZER;
 }  // namespace
 
@@ skipping 132 matching lines @@
   GetSnapshot(query, &snapshot);
   for (Histograms::iterator it = snapshot.begin();
        it != snapshot.end();
        ++it) {
     (*it)->WriteAscii(output);
     output->append("\n");
   }
 }
 
 // static
+void StatisticsRecorder::WriteJSON(const std::string& query,

[Alexei Svitkine (slow), 2013/11/02 00:05:26]

Can you add some unit tests for this?

[michaelpg, 2013/11/02 17:39:09]

Done.

+                                   std::string* output) {
+  if (!IsActive())
+    return;
+
+  *output = "{";
+  if (query.length()) {
+    output->append("\"query\":");
+    JsonDoubleQuote(query, true, output);
+    output->append(",");
+  }
+
+  Histograms snapshot;
+  GetSnapshot(query, &snapshot);
+  output->append("\"histograms\":[");
+  for (Histograms::iterator it = snapshot.begin();
+       it != snapshot.end();
+       ++it) {
+    std::string json;
+    (*it)->WriteJSON(&json);
+    output->append(json);
+    output->append(",");
+  }
+  // Remove trailing comma.
+  if (snapshot.size())
+    output->resize(output->size() - 1);
+
+  output->append("]}");
+}
+
+// static
 void StatisticsRecorder::GetHistograms(Histograms* output) {
   if (lock_ == NULL)
     return;
   base::AutoLock auto_lock(*lock_);
   if (histograms_ == NULL)
     return;
 
   for (HistogramMap::iterator it = histograms_->begin();
        histograms_->end() != it;
        ++it) {
@@ skipping 107 matching lines @@
 
 
 // static
 StatisticsRecorder::HistogramMap* StatisticsRecorder::histograms_ = NULL;
 // static
 StatisticsRecorder::RangesMap* StatisticsRecorder::ranges_ = NULL;
 // static
 base::Lock* StatisticsRecorder::lock_ = NULL;
 
 }  // namespace base