Change the logic for discarding all non-histogram logs because of actions/omnibox events to truncat…

components/metrics/metrics_log_unittest.cc

 // Copyright 2014 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 "components/metrics/metrics_log.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <string>
@@ skipping 395 matching lines @@
 
   TestMetricsServiceClient client;
   client.set_product(kTestProduct);
   TestMetricsLog log(
       kClientId, kSessionId, MetricsLog::ONGOING_LOG, &client, &prefs_);
   // Check that the product is set to |kTestProduct|.
   EXPECT_TRUE(log.uma_proto().has_product());
   EXPECT_EQ(kTestProduct, log.uma_proto().product());
 }
 
+TEST_F(MetricsLogTest, TruncateEvents) {
+  TestMetricsServiceClient client;
+  TestMetricsLog log(kClientId, kSessionId, MetricsLog::ONGOING_LOG, &client,
+                     &prefs_);
+
+  for (int i = 0; i < internal::kUserActionEventLimit * 2; ++i) {
+    log.RecordUserAction("BasicAction");
+    EXPECT_EQ(i + 1, log.uma_proto().user_action_event_size());
+  }
+
+  // Truncate, and check that the current size is the limit.
+  log.TruncateEvents();
+  EXPECT_EQ(internal::kUserActionEventLimit,
+            log.uma_proto().user_action_event_size());
+}

[Alexei Svitkine (slow), 2017/05/30 21:57:00]

Nit: Add one for omnibox events too. You can just add them directly to the proto
rather if there's no good API on the log to do it, like there is for user
actions.

[rkaplow, 2017/05/31 15:17:06]

Done.

+
 }  // namespace metrics