Added check for invalid histogram data, added additional diagnostics to find the source of troubles…

chrome/browser/chromeos/external_metrics.cc

Index: chrome/browser/chromeos/external_metrics.cc
diff --git a/chrome/browser/chromeos/external_metrics.cc b/chrome/browser/chromeos/external_metrics.cc
index ab5d2b4f8209760cb3ae4b00e180861f2768cc1d..01a91d632a3f08fa541af7e76d9a877c20d77c60 100644
--- a/chrome/browser/chromeos/external_metrics.cc
+++ b/chrome/browser/chromeos/external_metrics.cc
@@ -34,6 +34,17 @@ namespace chromeos {
 // The interval between external metrics collections in seconds
 static const int kExternalMetricsCollectionIntervalSeconds = 30;
 
+class SystemHistogram : public base::Histogram {
+ public:
+  static bool CheckValues(const std::string& name,
+                                           int minimum,
+                                           int maximum,
+                                           size_t bucket_count) {

[hshi1, 2012/08/03 02:24:24]

nit: please vertically left-align the arguments

[zel, 2012/08/03 02:29:45]

Done.

+    return base::Histogram::InspectConstructionArguments(
+        name, &minimum, &maximum, &bucket_count);
+  }
+};
+
 ExternalMetrics::ExternalMetrics()
     : test_recorder_(NULL) {
 }
@@ -89,6 +100,14 @@ void ExternalMetrics::RecordHistogram(const char* histogram_data) {
     LOG(ERROR) << "bad histogram request: " << histogram_data;
     return;
   }
+
+  if (!SystemHistogram::CheckValues(name, min, max, nbuckets)) {
+    LOG(ERROR) << "Invalid histogram " << name
+               << ", min=" << min
+               << ", max=" << max
+               << ", nbuckets=" << nbuckets;
+    return;
+  }
   // Do not use the UMA_HISTOGRAM_... macros here.  They cache the Histogram
   // instance and thus only work if |name| is constant.
   base::Histogram* counter = base::Histogram::FactoryGet(