Cache JumpList icons to avoid unnecessary creation and deletion

chrome/browser/win/jumplist_file_util_unittest.cc

 // 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_file_util.h"
 
 #include <string>
 
 #include "base/files/file_util.h"
 #include "base/files/scoped_temp_dir.h"
@@ skipping 82 matching lines @@
   // Sine the maximum files allowed to delete is 1, only 1 out of the 2
   // files is deleted. Therefore, the directory is not empty yet.
   DeleteDirectoryContent(dir_path, kFileDeleteLimitForTest);
   EXPECT_FALSE(base::IsDirectoryEmpty(dir_path));
 
   // Delete another file, and now the directory is empty.
   DeleteDirectoryContent(dir_path, kFileDeleteLimitForTest);
   EXPECT_TRUE(base::IsDirectoryEmpty(dir_path));
   EXPECT_TRUE(DirectoryExists(dir_path));
 }
+
+TEST_F(JumpListFileUtilTest, FilesExceedLimitInDir) {
+  base::FilePath dir_path = temp_dir_path();
+
+  // Create 2 files.
+  base::FilePath file_name =
+      dir_path.Append(FILE_PATH_LITERAL("TestFile1.txt"));
+  ASSERT_NO_FATAL_FAILURE(CreateTextFile(file_name, kFileContent));
+
+  file_name = dir_path.Append(FILE_PATH_LITERAL("TestFile2.txt"));
+  ASSERT_NO_FATAL_FAILURE(CreateTextFile(file_name, kFileContent));
+
+  EXPECT_TRUE(FilesExceedLimitInDir(dir_path, 1));
+  EXPECT_FALSE(FilesExceedLimitInDir(dir_path, 2));
+
+  DeleteDirectory(dir_path, kFileDeleteLimit);
+}
+
+TEST_F(JumpListFileUtilTest, DeleteNonCachedFiles) {
+  base::FilePath dir_path = temp_dir_path();
+
+  base::flat_set<base::FilePath> cached_files;
+
+  // Create 1 file and cache its filename.
+  base::FilePath file_name =
+      dir_path.Append(FILE_PATH_LITERAL("TestFile1.txt"));
+  ASSERT_NO_FATAL_FAILURE(CreateTextFile(file_name, kFileContent));
+
+  cached_files.insert(file_name);
+
+  // Create another file but not cache its filename.
+  file_name = dir_path.Append(FILE_PATH_LITERAL("TestFile2.txt"));
+  ASSERT_NO_FATAL_FAILURE(CreateTextFile(file_name, kFileContent));
+
+  // The second file created will be deleted as its filename is not in the
+  // cache, while the first file remains.
+  DeleteNonCachedFiles(dir_path, cached_files);
+  EXPECT_FALSE(base::IsDirectoryEmpty(dir_path));
+
+  // Clear the set and delete again, and now the first file should be gone.
+  cached_files.clear();
+  DeleteNonCachedFiles(dir_path, cached_files);
+  EXPECT_TRUE(base::IsDirectoryEmpty(dir_path));
+}