Handle the case where Purge is called while upload is in progress.

components/ukm/ukm_service.cc

 // Copyright 2017 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/ukm/ukm_service.h"
 
 #include <memory>
 #include <string>
 #include <utility>
 
@@ skipping 379 matching lines @@
 void UkmService::OnLogUploadComplete(int response_code) {
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK(log_upload_in_progress_);
   DVLOG(1) << "UkmService::OnLogUploadComplete";
   log_upload_in_progress_ = false;
 
   UMA_HISTOGRAM_SPARSE_SLOWLY("UKM.Upload.ResponseCode", response_code);
 
   bool upload_succeeded = response_code == 200;
 
-  // Provide boolean for error recovery (allow us to ignore response_code).
-  bool discard_log = false;
-  const size_t log_size_bytes = persisted_logs_.staged_log().length();
-  if (upload_succeeded) {
-    UMA_HISTOGRAM_COUNTS_10000("UKM.LogSize.OnSuccess", log_size_bytes / 1024);
-  } else if (response_code == 400) {
-    // Bad syntax.  Retransmission won't work.
-    discard_log = true;
-  }
+  // Staged log may have been deleted by Purge already, otherwise we may
+  // remove it from the log store here.
+  if (persisted_logs_.has_staged_log()) {
+    // Provide boolean for error recovery (allow us to ignore response_code).
+    bool discard_log = false;
+    const size_t log_size_bytes = persisted_logs_.staged_log().length();
+    if (upload_succeeded) {
+      UMA_HISTOGRAM_COUNTS_10000("UKM.LogSize.OnSuccess",
+                                 log_size_bytes / 1024);
+    } else if (response_code == 400) {
+      // Bad syntax.  Retransmission won't work.
+      discard_log = true;
+    }
 
-  if (upload_succeeded || discard_log) {
-    // TODO(holte): The if below is a temporary fix for a crash bug. We should
-    // revisit the logic and update it with a more correct fix. crbug.com/698819
-    if (persisted_logs_.has_staged_log())
+    if (upload_succeeded || discard_log) {
       persisted_logs_.DiscardStagedLog();
-    // Store the updated list to disk now that the removed log is uploaded.
-    persisted_logs_.PersistUnsentLogs();
+      // Store the updated list to disk now that the removed log is uploaded.
+      persisted_logs_.PersistUnsentLogs();
+    }
   }
 
   // Error 400 indicates a problem with the log, not with the server, so
   // don't consider that a sign that the server is in trouble.
   bool server_is_healthy = upload_succeeded || response_code == 400;
   scheduler_->UploadFinished(server_is_healthy,
                              persisted_logs_.has_unsent_logs());
 }
 
 void UkmService::RecordSource(std::unique_ptr<UkmSource> source) {
@@ skipping 63 matching lines @@
   }
   if (entries_.size() >= GetMaxEntries()) {
     RecordDroppedEntry(DroppedDataReason::MAX_HIT);
     return;
   }
 
   entries_.push_back(std::move(entry));
 }
 
 }  // namespace ukm