chrome_paths: refactor and sanitize cache directory handling

chrome/common/chrome_paths_mac.mm

 // Copyright (c) 2006-2008 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/common/chrome_paths_internal.h"
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/base_paths.h"
 #include "base/logging.h"
@@ skipping 30 matching lines @@
 #endif
     success = true;
   }
   return success;
 }
 
 bool GetUserDocumentsDirectory(FilePath* result) {
   return mac_util::GetUserDirectory(NSDocumentDirectory, result);
 }
 
+bool GetUserCacheDirectory(const FilePath& profile_dir, FilePath* result) {
+  // If the profile directory is under ~/Library/Application Support,
+  // use a suitable cache directory under ~/Library/Caches.  For
+  // example, a profile directory of ~/Library/Application
+  // Support/Google/Chrome/MyProfileName would use the cache directory
+  // ~/Library/Caches/Google/Chrome/MyProfileName.
+
+  FilePath cache_dir;
+  if (!mac_util::GetUserDirectory(NSCachesDirectory, &cache_dir))
+    return false;
+
+  FilePath app_data_dir;
+  if (PathService::Get(base::DIR_APP_DATA, &app_data_dir)) {
+    FilePath system_relative_dir = cache_dir;

[Mark Mentovai, 2010/11/18 16:54:54]

Do you need this copy? Why don’t you just move the GetUserDirectory call right
here and have it fill in system_relative_dir?

[Evan Martin, 2010/11/18 18:13:07]

I found the usage of AppendRelativePath kind of hard to follow, so I thought the
extra naming would help.  I'll try a different approach.

+    if (app_data_dir.AppendRelativePath(profile_dir, &system_relative_dir)) {
+      *result = system_relative_dir;
+      return true;
+    }
+  }
+
+  *result = profile_dir;
+  return true;
+}
+
 bool GetUserDownloadsDirectory(FilePath* result) {
   return mac_util::GetUserDirectory(NSDownloadsDirectory, result);
 }
 
 bool GetUserDesktop(FilePath* result) {
   return mac_util::GetUserDirectory(NSDesktopDirectory, result);
 }
 
 FilePath GetVersionedDirectory() {
   if (g_override_versioned_directory)
@@ skipping 42 matching lines @@
   // The framework bundle is at a known path and name from the browser .app's
   // versioned directory.
   return GetVersionedDirectory().Append(kFrameworkName);
 }
 
 bool GetLocalLibraryDirectory(FilePath* result) {
   return mac_util::GetLocalDirectory(NSLibraryDirectory, result);
 }
 
 }  // namespace chrome