Upstream Chrome on iOS source code [5/11].

ios/chrome/browser/ui/history/history_util.mm

Index: ios/chrome/browser/ui/history/history_util.mm
diff --git a/ios/chrome/browser/ui/history/history_util.mm b/ios/chrome/browser/ui/history/history_util.mm
new file mode 100644
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--- /dev/null
+++ b/ios/chrome/browser/ui/history/history_util.mm
@@ -0,0 +1,72 @@
+// Copyright 2016 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 "ios/chrome/browser/ui/history/history_util.h"
+
+#include <map>
+
+#include "base/i18n/time_formatting.h"
+#include "base/time/time.h"
+#include "components/strings/grit/components_strings.h"
+#include "ios/chrome/browser/ui/history/history_entry.h"
+#include "ui/base/l10n/l10n_util.h"
+#include "ui/base/l10n/time_format.h"
+#include "url/gurl.h"
+
+namespace history {
+
+base::string16 GetRelativeDateLocalized(const base::Time& visit_time) {
+  base::Time midnight = base::Time::Now().LocalMidnight();
+  base::string16 date_str = ui::TimeFormat::RelativeDate(visit_time, &midnight);
+  if (date_str.empty()) {
+    date_str = base::TimeFormatFriendlyDate(visit_time);
+  } else {
+    date_str = l10n_util::GetStringFUTF16(
+        IDS_HISTORY_DATE_WITH_RELATIVE_TIME, date_str,
+        base::TimeFormatFriendlyDate(visit_time));
+  }
+  return date_str;
+}
+
+void MergeDuplicateHistoryEntries(std::vector<history::HistoryEntry>* entries) {
+  std::vector<history::HistoryEntry> new_entries;
+  // Pre-reserve the size of the new vector. Since we're working with pointers
+  // later on not doing this could lead to the vector being resized and to
+  // pointers to invalid locations.
+  new_entries.reserve(entries->size());
+  // Maps a URL to the most recent entry on a particular day.
+  std::map<GURL, history::HistoryEntry*> current_day_entries;
+
+  // Keeps track of the day that |current_day_urls| is holding the URLs for,
+  // in order to handle removing per-day duplicates.
+  base::Time current_day_midnight;
+
+  std::sort(entries->begin(), entries->end(),
+            history::HistoryEntry::SortByTimeDescending);
+
+  for (const history::HistoryEntry& entry : *entries) {
+    // Reset the list of found URLs when a visit from a new day is encountered.
+    if (current_day_midnight != entry.time.LocalMidnight()) {
+      current_day_entries.clear();
+      current_day_midnight = entry.time.LocalMidnight();
+    }
+
+    // Keep this visit if it's the first visit to this URL on the current day.
+    if (current_day_entries.count(entry.url) == 0) {
+      new_entries.push_back(entry);
+      current_day_entries[entry.url] = &new_entries.back();
+    } else {
+      // Keep track of the timestamps of all visits to the URL on the same day.
+      history::HistoryEntry* combined_entry = current_day_entries[entry.url];
+      combined_entry->all_timestamps.insert(entry.all_timestamps.begin(),
+                                            entry.all_timestamps.end());
+
+      if (combined_entry->entry_type != entry.entry_type) {
+        combined_entry->entry_type = history::HistoryEntry::COMBINED_ENTRY;
+      }
+    }
+  }
+  entries->swap(new_entries);
+}
+}  // namespace history