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

ios/chrome/today_extension/today_metrics_logger.mm

 // Copyright 2015 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.
 
 #import <UIKit/UIKit.h>
 
 #import "ios/chrome/today_extension/today_metrics_logger.h"
 
 #include "base/base64.h"
 #include "base/cpu.h"
@@ skipping 28 matching lines @@
 
 // User default key to keep track of the current log session ID. Increased every
 // time a log is created. This ID must be offset using
 // app_group::AppGroupSessionID.
 NSString* const kTodayExtensionMetricsSessionID = @"MetricsSessionID";
 
 // User default key to the current log serialized. In case of an extension
 // restart, this log can be written to disk for upload.
 NSString* const kTodayExtensionMetricsCurrentLog = @"MetricsCurrentLog";
 
-// Maximum number of event in a log.
-const int kMaxEventsPerLog = 1000;
-
 // Maximum age of a log.
 const int kMaxLogLifeTimeInSeconds = 86400;
 
 // A simple implementation of metrics::MetricsServiceClient.
 // As logs are uploaded by Chrome application, not all methods are needed.
 // Only the method needed to initialize the metrics logs are implementsd.
 class TodayMetricsServiceClient : public metrics::MetricsServiceClient {
  public:
   TodayMetricsServiceClient() {}
   metrics::MetricsService* GetMetricsService() override;
@@ skipping 138 matching lines @@
   histogram_snapshot_manager_.PrepareDeltas(
       base::StatisticsRecorder::begin(false), base::StatisticsRecorder::end(),
       base::Histogram::kNoFlags, base::Histogram::kNoFlags);
   std::string encoded_log;
   log_->GetOpenEncodedLog(&encoded_log);
   NSData* ns_encoded_log =
       [NSData dataWithBytes:encoded_log.c_str() length:encoded_log.length()];
   [[NSUserDefaults standardUserDefaults]
       setObject:ns_encoded_log
          forKey:kTodayExtensionMetricsCurrentLog];
-  if (log_->num_events() >= kMaxEventsPerLog ||
-      (base::TimeTicks::Now() - log_->creation_time()).InSeconds() >=
-          kMaxLogLifeTimeInSeconds) {
+  log_->TruncateEvents();
+  if ((base::TimeTicks::Now() - log_->creation_time()).InSeconds() >=
+      kMaxLogLifeTimeInSeconds) {
     CreateNewLog();
   }
 }
 
 bool TodayMetricsLogger::CreateNewLog() {
   id previous_log = [[NSUserDefaults standardUserDefaults]
       dataForKey:kTodayExtensionMetricsCurrentLog];
   if (previous_log) {
     app_group::client_app::AddPendingLog(previous_log,
                                          app_group::APP_GROUP_TODAY_EXTENSION);
@@ skipping 75 matching lines @@
 void TodayMetricsLogger::UniqueInconsistencyDetected(
     base::HistogramBase::Inconsistency problem) {
   UMA_HISTOGRAM_ENUMERATION("Histogram.InconsistenciesBrowserUnique", problem,
                             base::HistogramBase::NEVER_EXCEEDED_VALUE);
 }
 
 void TodayMetricsLogger::InconsistencyDetectedInLoggedCount(int amount) {
   UMA_HISTOGRAM_COUNTS("Histogram.InconsistentSnapshotBrowser",
                        std::abs(amount));
 }