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 56 matching lines @@
         prefs_(prefs) {
     InitPrefs();
   }
 
   ~TestMetricsLog() override {}
 
   const ChromeUserMetricsExtension& uma_proto() const {
     return *MetricsLog::uma_proto();
   }
 
+  ChromeUserMetricsExtension* mutable_uma_proto() {
+    return MetricsLog::uma_proto();
+  }
+
   const SystemProfileProto& system_profile() const {
     return uma_proto().system_profile();
   }
 
  private:
   void InitPrefs() {
     prefs_->SetString(prefs::kMetricsReportingEnabledTimestamp,
                       base::Int64ToString(kEnabledDate));
   }
 
@@ skipping 319 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());
+  }
+  for (int i = 0; i < internal::kOmniboxEventLimit * 2; ++i) {
+    // Add an empty omnibox event. Not fully realistic since these are normally
+    // supplied by a metrics provider.
+    log.mutable_uma_proto()->add_omnibox_event();
+    EXPECT_EQ(i + 1, log.uma_proto().omnibox_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());
+  EXPECT_EQ(internal::kOmniboxEventLimit, log.uma_proto().omnibox_event_size());
+}
+
 }  // namespace metrics