SSLClientSessionCache: Log number of times Lookup is called per Session.

net/ssl/ssl_client_session_cache_unittest.cc

Index: net/ssl/ssl_client_session_cache_unittest.cc
diff --git a/net/ssl/ssl_client_session_cache_unittest.cc b/net/ssl/ssl_client_session_cache_unittest.cc
index c9cf6f28c4f19ff4d4f50cadad90c42cfc45584c..d943c1bf1e7501feb547fbcabb50af5611a8b278 100644
--- a/net/ssl/ssl_client_session_cache_unittest.cc
+++ b/net/ssl/ssl_client_session_cache_unittest.cc
@@ -7,6 +7,7 @@
 #include "base/memory/ptr_util.h"
 #include "base/run_loop.h"
 #include "base/strings/string_number_conversions.h"
+#include "base/test/histogram_tester.h"
 #include "base/test/simple_test_clock.h"
 #include "base/time/time.h"
 #include "base/trace_event/memory_allocator_dump.h"
@@ -87,6 +88,37 @@ TEST(SSLClientSessionCacheTest, Basic) {
   EXPECT_EQ(1u, session3->references);
 }
 
+// Test that the Net.SSLSessionLookupCount histogram logs calls to Lookup.
+TEST(SSLClientSessionCacheTest, LookupCountUMA) {
+  const char kLookupCountHistogram[] = "Net.SSLSessionLookupCount";
+  base::HistogramTester histograms;
+
+  SSLClientSessionCache::Config config;
+  SSLClientSessionCache cache(config);
+
+  histograms.ExpectTotalCount(kLookupCountHistogram, 0);
+
+  bssl::UniquePtr<SSL_SESSION> session1(SSL_SESSION_new());
+  bssl::UniquePtr<SSL_SESSION> session2(SSL_SESSION_new());
+  cache.Insert("key1", session1.get());
+  cache.Insert("key2", session2.get());
+  histograms.ExpectBucketCount(kLookupCountHistogram, 0, 2);
+
+  EXPECT_EQ(session1.get(), cache.Lookup("key1").get());
+  histograms.ExpectBucketCount(kLookupCountHistogram, 1, 1);
+
+  EXPECT_EQ(session1.get(), cache.Lookup("key1").get());
+  histograms.ExpectBucketCount(kLookupCountHistogram, 2, 1);
+
+  EXPECT_EQ(session2.get(), cache.Lookup("key2").get());
+  histograms.ExpectBucketCount(kLookupCountHistogram, 1, 2);
+  // The total value is number of Inserts + number of Lookups, since "0 Lookups"
+  // is recorded on Insert.
+  histograms.ExpectTotalCount(kLookupCountHistogram, 5);
+
+  EXPECT_EQ(2u, cache.size());
+}
+
 // Test that a session may be inserted at two different keys. This should never
 // be necessary, but the API doesn't prohibit it.
 TEST(SSLClientSessionCacheTest, DoubleInsert) {