Match only prefixes of histogram names.

base/test/histogram_tester.cc

Index: base/test/histogram_tester.cc
diff --git a/base/test/histogram_tester.cc b/base/test/histogram_tester.cc
index 90981e232637f8eb3323c96f9f22dc9538c5b89a..907e08b5d7def7b5158ad13f93c85eef352da1b1 100644
--- a/base/test/histogram_tester.cc
+++ b/base/test/histogram_tester.cc
@@ -11,6 +11,7 @@
 #include "base/metrics/metrics_hashes.h"
 #include "base/metrics/sample_map.h"
 #include "base/metrics/statistics_recorder.h"
+#include "base/strings/string_util.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace base {
@@ -113,6 +114,8 @@ HistogramTester::CountsMap HistogramTester::GetTotalCountsForPrefix(
 
   CountsMap result;
   for (base::HistogramBase* histogram : query_matches) {

[Ilya Sherman, 2017/01/12 20:32:41]

Optional nit: While you're here, it would be nice to drop this unnecessary use
of the "base::" namespace.

[pkalinnikov, 2017/01/13 10:28:59]

Done here and throughout this file and its header.

+    if (!StartsWith(histogram->histogram_name(), query, CompareCase::SENSITIVE))
+      continue;
     std::unique_ptr<HistogramSamples> new_samples =
         GetHistogramSamplesSinceCreation(histogram->histogram_name());
     // Omit unchanged histograms from the result.