Histogram - add check for external LinearHistogram data with mismatching range.

This adds an extra step of validation for LinearHistogram data (also known as enum data)
coming from an external data source: if a histogram already exists for the specified name
but the range of the new data does not match the existing histogram, then discard the
new data to prevent crashing chrome.

BUG=143714


Review URL: https://chromiumcodereview.appspot.com/10917080

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@154887 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 10 insertions, 1 deletions

diff --git a/chrome/browser/chromeos/external_metrics.cc b/chrome/browser/chromeos/external_metrics.cc
index bdb4b5e..138cfcc 100644
--- a/chrome/browser/chromeos/external_metrics.cc
+++ b/chrome/browser/chromeos/external_metrics.cc
@@ -19,6 +19,7 @@
 #include "base/bind.h"
 #include "base/eintr_wrapper.h"
 #include "base/metrics/histogram.h"
+#include "base/metrics/statistics_recorder.h"
 #include "base/perftimer.h"
 #include "base/time.h"
 #include "chrome/browser/browser_process.h"
@@ -43,6 +44,14 @@ class SystemHistogram : public base::Histogram {
     return base::Histogram::InspectConstructionArguments(
         name, &minimum, &maximum, &bucket_count);
   }
+  static bool CheckLinearValues(const std::string& name, int maximum) {
+    if (!CheckValues(name, 1, maximum, maximum + 1))
+      return false;
+    Histogram* histogram = base::StatisticsRecorder::FindHistogram(name);
+    if (!histogram)
+      return true;
+    return histogram->HasConstructionArguments(1, maximum, maximum + 1);
+  }
 };
 
 ExternalMetrics::ExternalMetrics()
@@ -124,7 +133,7 @@ void ExternalMetrics::RecordLinearHistogram(const char* histogram_data) {
     return;
   }
 
-  if (!SystemHistogram::CheckValues(name, 1, max, max + 1)) {
+  if (!SystemHistogram::CheckLinearValues(name, max)) {
     LOG(ERROR) << "Invalid linear histogram " << name
                << ", max=" << max;
     return;