Cancel the JumpList update if top 5 most visited URLs are unchanged

chrome/browser/win/jumplist_update_util_unittest.cc

Index: chrome/browser/win/jumplist_update_util_unittest.cc
diff --git a/chrome/browser/win/jumplist_update_util_unittest.cc b/chrome/browser/win/jumplist_update_util_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..5ae46c08153e8feb2f9536605255506c9b837728
--- /dev/null
+++ b/chrome/browser/win/jumplist_update_util_unittest.cc
@@ -0,0 +1,74 @@
+// Copyright (c) 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 "chrome/browser/win/jumplist_update_util.h"
+
+#include <algorithm>
+
+#include "base/strings/utf_string_conversions.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace {
+
+// Test data.
+static constexpr struct {

[grt (UTC plus 2), 2017/05/31 06:59:53]

move this into the test function as per
https://google.github.io/styleguide/cppguide.html#Local_Variables

[chengx, 2017/05/31 20:46:22]

Done.

+  const char* url;
+  const wchar_t* title;
+} kTestData[] = {{"https://www.google.com/", L"Google"},
+                 {"https://www.youtube.com/", L"Youtube"},
+                 {"https://www.gmail.com/", L"Gmail"}};
+
+// Helper function to create a ShellLinkItem whose url is specified by |url|.
+scoped_refptr<ShellLinkItem> CreateShellLinkWithURL(const std::string& url) {
+  auto item = base::MakeRefCounted<ShellLinkItem>();
+  item->set_url(url);
+  return item;
+}
+
+}  // namespace
+
+TEST(JumpListUpdateUtilTest, MostVisitedItemsUnchanged) {
+  // Initialize jumplist_items and history_items using kTestData.
+  ShellLinkItemList jumplist_items;
+  history::MostVisitedURLList history_items;
+  for (const auto& pair : kTestData) {

[grt (UTC plus 2), 2017/05/31 06:59:53]

nit: pair -> test_data or something

[chengx, 2017/05/31 20:46:22]

Done.

+    jumplist_items.push_back(CreateShellLinkWithURL(pair.url));
+    GURL url(pair.url);

[grt (UTC plus 2), 2017/05/31 06:59:53]

replace these next three lines with:
    history_items.emplace_back(GURL(pair.url), pair.title);

[chengx, 2017/05/31 20:46:22]

This is super handy! Thanks!

+    history::MostVisitedURL most_visited_url(url, pair.title);
+    history_items.push_back(most_visited_url);
+  }
+
+  // Both jumplist_items and history_items have 3 urls: Google, Youtube, Gmail.
+  // Also, their urls have the same order.
+  EXPECT_TRUE(MostVisitedItemsUnchanged(jumplist_items, history_items, 3));
+  EXPECT_FALSE(MostVisitedItemsUnchanged(jumplist_items, history_items, 2));
+  EXPECT_FALSE(MostVisitedItemsUnchanged(jumplist_items, history_items, 1));
+
+  // Reverse history_items, so the 3 urls in history_items are in reverse order:
+  // Gmail, Youtube, Google.
+  // The 3 urls in jumplist_items remain the same: Google, Youtube, Gmail.
+  std::reverse(history_items.begin(), history_items.end());
+  EXPECT_FALSE(MostVisitedItemsUnchanged(jumplist_items, history_items, 3));
+
+  // Reverse history_items back.
+  std::reverse(history_items.begin(), history_items.end());
+  EXPECT_TRUE(MostVisitedItemsUnchanged(jumplist_items, history_items, 3));
+
+  // Pop out the last url ("Gmail") from jumplist_items.
+  // Now jumplist_items has 2 urls: Google, Youtube,
+  // and history_items has 3 urls: Google, Youtube, Gmail.
+  jumplist_items.pop_back();
+  EXPECT_FALSE(MostVisitedItemsUnchanged(jumplist_items, history_items, 3));
+  EXPECT_TRUE(MostVisitedItemsUnchanged(jumplist_items, history_items, 2));
+  EXPECT_FALSE(MostVisitedItemsUnchanged(jumplist_items, history_items, 1));
+
+  // Pop out the last two urls ("Youtube", "Gmail") from history_items.
+  // Now jumplist_items has 2 urls: Google, Youtube,
+  // and history_items has 1 url: Google.
+  history_items.pop_back();
+  history_items.pop_back();
+  EXPECT_FALSE(MostVisitedItemsUnchanged(jumplist_items, history_items, 3));
+  EXPECT_FALSE(MostVisitedItemsUnchanged(jumplist_items, history_items, 2));
+  EXPECT_FALSE(MostVisitedItemsUnchanged(jumplist_items, history_items, 1));
+}