Try to detect internal corruption of histogram instances....

chrome/common/metrics_helpers.cc

 // Copyright (c) 2010 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 "chrome/common/metrics_helpers.h"
 
 #if defined(USE_SYSTEM_LIBBZ2)
 #include <bzlib.h>
 #else
 #include "third_party/bzip2/bzlib.h"
@@ skipping 466 matching lines @@
        ++it) {
     if ((*it)->flags() & Histogram::kUmaTargetedHistogramFlag)
       RecordHistogram(**it);
   }
 }
 
 void MetricsServiceBase::RecordHistogram(const Histogram& histogram) {
   // Get up-to-date snapshot of sample stats.
   Histogram::SampleSet snapshot;
   histogram.SnapshotSample(&snapshot);
+  const std::string& histogram_name = histogram.histogram_name();
 
-  const std::string& histogram_name = histogram.histogram_name();
+  int corruption = histogram.FindCorruption(snapshot);
+  if (corruption) {
+    NOTREACHED();
+    // Don't send corrupt data to metrics survices.
+    UMA_HISTOGRAM_ENUMERATION("Histogram.InconsistenciesBrowser",
+                              corruption, Histogram::NEVER_EXCEEDED_VALUE);
+    typedef std::map<std::string, int> ProblemMap;
+    static ProblemMap* inconsistencies = new ProblemMap;
+    int old_corruption = (*inconsistencies)[histogram_name];
+    if (old_corruption == (corruption | old_corruption))
+      return;  // We've already seen this corruption for this histogram.
+    (*inconsistencies)[histogram_name] |= corruption;
+    UMA_HISTOGRAM_ENUMERATION("Histogram.InconsistenciesBrowserUnique",
+                              corruption, Histogram::NEVER_EXCEEDED_VALUE);
+    return;
+  }
 
   // Find the already sent stats, or create an empty set.
   LoggedSampleMap::iterator it = logged_samples_.find(histogram_name);
   Histogram::SampleSet* already_logged;
   if (logged_samples_.end() == it) {
     // Add new entry
     already_logged = &logged_samples_[histogram.histogram_name()];
     already_logged->Resize(histogram);  // Complete initialization.
   } else {
     already_logged = &(it->second);
@@ skipping 10 matching lines @@
   }
 }
 
 void MetricsServiceBase::DiscardPendingLog() {
   if (pending_log_) {  // Shutdown might have deleted it!
     delete pending_log_;
     pending_log_ = NULL;
   }
   compressed_log_.clear();
 }