drive: prefetcher compares last modified time in addition to last access time.

chrome/browser/chromeos/drive/drive_prefetcher.h

 // Copyright (c) 2012 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 CHROME_BROWSER_CHROMEOS_DRIVE_DRIVE_PREFETCHER_H_
 #define CHROME_BROWSER_CHROMEOS_DRIVE_DRIVE_PREFETCHER_H_
 
 #include <set>
 #include <deque>
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
+#include "chrome/browser/chromeos/drive/drive.pb.h"
 #include "chrome/browser/chromeos/drive/drive_file_system_interface.h"
 #include "chrome/browser/chromeos/drive/drive_file_system_observer.h"
 #include "chrome/browser/chromeos/drive/drive_sync_client_observer.h"
 #include "chrome/browser/google_apis/gdata_errorcode.h"
 
 class FilePath;
 
 namespace drive {
 
-class DriveEntryProto;
 class DriveFileSystemInterface;
 
 // The parameters for DrivePrefetcher construction.
 struct DrivePrefetcherOptions {
   DrivePrefetcherOptions();  // Sets the default values.
 
   int initial_prefetch_count;
   int64 prefetch_file_size_limit;
 };
 
@@ skipping 37 matching lines @@
   // Helper methods to traverse over the file system.
   void VisitFile(const DriveEntryProto& entry);
   void VisitDirectory(const FilePath& directory_path);
   void OnReadDirectory(const FilePath& directory_path,
                        DriveFileError error,
                        bool hide_hosted_documents,
                        scoped_ptr<DriveEntryProtoVector> entries);
   void OnReadDirectoryFinished();
 
   // Keeps the kNumberOfLatestFilesToKeepInCache latest files in the filesystem.
-  typedef std::set<std::pair<int64, std::string> > LatestFileSet;
+  typedef bool (*PrefetchPriorityComparator)(const DriveEntryProto&,
+                                             const DriveEntryProto&);
+  typedef std::set<DriveEntryProto, PrefetchPriorityComparator> LatestFileSet;
   LatestFileSet latest_files_;
 
   // The queue of files to fetch. Files with higher priority comes front.
   std::deque<std::string> queue_;
 
   // Number of in-flight |ExecuteOnePrefetch| calls that has not finished yet.
   int number_of_inflight_prefetches_;
 
   // Number of in-flight |VisitDirectory| calls that has not finished yet.
   int number_of_inflight_traversals_;
@@ skipping 14 matching lines @@
 
   // Note: This should remain the last member so it'll be destroyed and
   // invalidate its weak pointers before any other members are destroyed.
   base::WeakPtrFactory<DrivePrefetcher> weak_ptr_factory_;
   DISALLOW_COPY_AND_ASSIGN(DrivePrefetcher);
 };
 
 }  // namespace drive
 
 #endif  // CHROME_BROWSER_CHROMEOS_DRIVE_DRIVE_PREFETCHER_H_