[Paint Preview] Make DirectoryKey a class

The previous implementation of DirectoryKey used a const string making
it largely incompatible with <algorithm> which I intend to make use of
in a few places. To fix this it should be made into a class that can
be copied and swapped, but with only a constant accessor.

Bug: 1058093
Change-Id: Ib3aff42e248910bd78b9a00c98777fd670999d37
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2084724Reviewed-by: Mehran Mahmoudi <mahmoudi@chromium.org>
Commit-Queue: Calder Kitagawa <ckitagawa@chromium.org>
Cr-Commit-Position: refs/heads/master@{#746501}

components/paint_preview/browser/BUILD.gn

@@ -10,6 +10,8 @@ source_set("browser") {
   sources = [
     "compositor_utils.cc",
     "compositor_utils.h",
+    "directory_key.cc",
+    "directory_key.h",
     "file_manager.cc",
     "file_manager.h",
     "hit_tester.cc",

components/paint_preview/browser/directory_key.cc

+// Copyright 2020 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/paint_preview/browser/directory_key.h"
+
+namespace paint_preview {
+
+bool operator<(const DirectoryKey& a, const DirectoryKey& b) {
+  return a.AsciiDirname() < b.AsciiDirname();
+}
+
+}  // namespace paint_preview

components/paint_preview/browser/directory_key.h

+// Copyright 2020 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.
+
+#ifndef COMPONENTS_PAINT_PREVIEW_BROWSER_DIRECTORY_KEY_H_
+#define COMPONENTS_PAINT_PREVIEW_BROWSER_DIRECTORY_KEY_H_
+
+#include <string>
+
+#include "base/strings/string_piece.h"
+
+namespace paint_preview {
+
+// A key for a specific subdirectory (== captured paint preview).
+class DirectoryKey {
+ public:
+  DirectoryKey() = default;
+  explicit DirectoryKey(base::StringPiece ascii_dirname)
+      : ascii_dirname_(ascii_dirname) {}
+  ~DirectoryKey() = default;
+
+  const std::string& AsciiDirname() const { return ascii_dirname_; }
+
+ private:
+  std::string ascii_dirname_;
+};
+
+bool operator<(const DirectoryKey& a, const DirectoryKey& b);
+
+}  // namespace paint_preview
+
+#endif  // COMPONENTS_PAINT_PREVIEW_BROWSER_DIRECTORY_KEY_H_

components/paint_preview/browser/file_manager.cc

@@ -40,7 +40,7 @@ size_t FileManager::GetSizeOfArtifacts(const DirectoryKey& key) {
   switch (storage_type) {
     case kDirectory: {
       return base::ComputeDirectorySize(
-          root_directory_.AppendASCII(key.ascii_dirname));
+          root_directory_.AppendASCII(key.AsciiDirname()));
     }
     case kZip: {
       int64_t file_size = 0;
@@ -91,7 +91,7 @@ bool FileManager::CreateOrGetDirectory(const DirectoryKey& key,
   StorageType storage_type = GetPathForKey(key, &path);
   switch (storage_type) {
     case kNone: {
-      base::FilePath new_path = root_directory_.AppendASCII(key.ascii_dirname);
+      base::FilePath new_path = root_directory_.AppendASCII(key.AsciiDirname());
       base::File::Error error = base::File::FILE_OK;
       if (base::CreateDirectoryAndGetError(new_path, &error)) {
         *directory = new_path;
@@ -106,7 +106,7 @@ bool FileManager::CreateOrGetDirectory(const DirectoryKey& key,
       return true;
     }
     case kZip: {
-      base::FilePath dst_path = root_directory_.AppendASCII(key.ascii_dirname);
+      base::FilePath dst_path = root_directory_.AppendASCII(key.AsciiDirname());
       base::File::Error error = base::File::FILE_OK;
       if (!base::CreateDirectoryAndGetError(dst_path, &error)) {
         DVLOG(1) << "ERROR: failed to create directory: " << path
@@ -185,7 +185,7 @@ std::unique_ptr<PaintPreviewProto> FileManager::DeserializePaintPreviewProto(
 FileManager::StorageType FileManager::GetPathForKey(const DirectoryKey& key,
                                                     base::FilePath* path) {
   base::FilePath directory_path =
-      root_directory_.AppendASCII(key.ascii_dirname);
+      root_directory_.AppendASCII(key.AsciiDirname());
   if (base::PathExists(directory_path)) {
     *path = directory_path;
     return kDirectory;

components/paint_preview/browser/file_manager.h

@@ -5,19 +5,14 @@
 #ifndef COMPONENTS_PAINT_PREVIEW_BROWSER_FILE_MANAGER_H_
 #define COMPONENTS_PAINT_PREVIEW_BROWSER_FILE_MANAGER_H_
 
-#include <string>
-
 #include "base/files/file_path.h"
 #include "base/time/time.h"
+#include "components/paint_preview/browser/directory_key.h"
 #include "components/paint_preview/common/proto/paint_preview.pb.h"
 #include "url/gurl.h"
 
 namespace paint_preview {
 
-struct DirectoryKey {
-  const std::string ascii_dirname;
-};
-
 // Manages paint preview files associated with a root directory typically the
 // root directory is <profile_dir>/paint_previews/<feature>.
 class FileManager {

components/paint_preview/player/player_compositor_delegate.h

@@ -24,7 +24,7 @@ class SkBitmap;
 
 namespace paint_preview {
 
-struct DirectoryKey;
+class DirectoryKey;
 
 class PlayerCompositorDelegate {
  public: