Remove DrivePrefetcher and relevant flags.

chrome/browser/chromeos/drive/drive_prefetcher.cc

Index: chrome/browser/chromeos/drive/drive_prefetcher.cc
diff --git a/chrome/browser/chromeos/drive/drive_prefetcher.cc b/chrome/browser/chromeos/drive/drive_prefetcher.cc
deleted file mode 100644
index a79dfaa90896429787efbd0411610095215a1e1e..0000000000000000000000000000000000000000
--- a/chrome/browser/chromeos/drive/drive_prefetcher.cc
+++ /dev/null
@@ -1,193 +0,0 @@
-// 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.
-
-#include "chrome/browser/chromeos/drive/drive_prefetcher.h"
-
-#include "base/bind.h"
-#include "base/command_line.h"
-#include "base/stringprintf.h"
-#include "chrome/browser/chromeos/drive/drive_file_system_interface.h"
-#include "chrome/browser/chromeos/drive/file_system_util.h"
-#include "chrome/browser/chromeos/drive/logging.h"
-#include "chrome/common/chrome_switches.h"
-#include "content/public/browser/browser_thread.h"
-
-using content::BrowserThread;
-
-namespace drive {
-
-namespace {
-
-const int kInitialPrefetchCount = 100;
-const int64 kPrefetchFileSizeLimit = 10 << 20;  // 10MB
-
-// Returns true if prefetching is enabled by a command line option.
-bool IsPrefetchEnabled() {
-  return CommandLine::ForCurrentProcess()->HasSwitch(
-      switches::kEnableDrivePrefetch);
-}
-
-// Returns true if |left| has lower priority than |right|.
-bool ComparePrefetchPriority(const DriveEntryProto& left,
-                             const DriveEntryProto& right) {
-  // First, compare last access time. The older entry has less priority.
-  if (left.file_info().last_accessed() != right.file_info().last_accessed())
-    return left.file_info().last_accessed() < right.file_info().last_accessed();
-
-  // When the entries have the same last access time (which happens quite often
-  // because Drive server doesn't set the field until an entry is viewed via
-  // drive.google.com), we use last modified time as the tie breaker.
-  if (left.file_info().last_modified() != right.file_info().last_modified())
-    return left.file_info().last_modified() < right.file_info().last_modified();
-
-  // Two entries have the same priority. To make this function a valid
-  // comparator for std::set, we need to differentiate them anyhow.
-  return left.resource_id() < right.resource_id();
-}
-
-}
-
-DrivePrefetcherOptions::DrivePrefetcherOptions()
-    : initial_prefetch_count(kInitialPrefetchCount),
-      prefetch_file_size_limit(kPrefetchFileSizeLimit) {
-}
-
-DrivePrefetcher::DrivePrefetcher(DriveFileSystemInterface* file_system,
-                                 const DrivePrefetcherOptions& options)
-    : latest_files_(&ComparePrefetchPriority),
-      number_of_inflight_traversals_(0),
-      initial_prefetch_count_(options.initial_prefetch_count),
-      prefetch_file_size_limit_(options.prefetch_file_size_limit),
-      file_system_(file_system),
-      weak_ptr_factory_(ALLOW_THIS_IN_INITIALIZER_LIST(this)) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-
-  // The flag controls whether or not the prefetch observe the file system. When
-  // it is disabled, no event (except the direct call of OnInitialLoadFinished
-  // in the unit test code) will trigger the prefetcher.
-  if (IsPrefetchEnabled())
-    file_system_->AddObserver(this);
-}
-
-DrivePrefetcher::~DrivePrefetcher() {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-  if (IsPrefetchEnabled())
-    file_system_->RemoveObserver(this);
-}
-
-void DrivePrefetcher::OnInitialLoadFinished() {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-
-  StartPrefetcherCycle();
-}
-
-void DrivePrefetcher::OnDirectoryChanged(const base::FilePath& directory_path) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-
-  // TODO(kinaba): crbug.com/156270.
-  // Update the list of latest files and the prefetch queue if needed.
-}
-
-void DrivePrefetcher::StartPrefetcherCycle() {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-
-  // Scans the filesystem. When it is finished, DoPrefetch() will be called.
-  VisitDirectory(util::GetDriveMyDriveRootPath());
-}
-
-void DrivePrefetcher::DoPrefetch() {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-
-  for (LatestFileSet::reverse_iterator it = latest_files_.rbegin();
-      it != latest_files_.rend(); ++it) {
-    const std::string& resource_id = it->resource_id();
-    util::Log("Prefetcher: Enqueue prefetching %s", resource_id.c_str());
-    file_system_->GetFileByResourceId(
-        resource_id,
-        DriveClientContext(PREFETCH),
-        base::Bind(&DrivePrefetcher::OnPrefetchFinished,
-                   weak_ptr_factory_.GetWeakPtr(),
-                   resource_id),
-        google_apis::GetContentCallback());
-  }
-}
-
-void DrivePrefetcher::OnPrefetchFinished(const std::string& resource_id,
-                                         FileError error,
-                                         const base::FilePath& file_path,
-                                         const std::string& mime_type,
-                                         DriveFileType file_type) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-  if (error != FILE_ERROR_OK)
-    LOG(WARNING) << "Prefetch failed: " << FileErrorToString(error);
-  util::Log("Prefetcher: Finish fetching (%s) %s",
-            FileErrorToString(error).c_str(),
-            resource_id.c_str());
-}
-
-void DrivePrefetcher::VisitFile(const DriveEntryProto& entry) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-
-  // Excessively large files will not be fetched.
-  if (entry.file_info().size() > prefetch_file_size_limit_)
-    return;
-
-  // Remember the file in the set ordered by the |last_accessed| field.
-  latest_files_.insert(entry);
-  // If the set become too big, forget the oldest entry.
-  if (latest_files_.size() > static_cast<size_t>(initial_prefetch_count_))
-    latest_files_.erase(latest_files_.begin());
-}
-
-void DrivePrefetcher::VisitDirectory(const base::FilePath& directory_path) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-
-  ++number_of_inflight_traversals_;
-  file_system_->ReadDirectoryByPath(
-      directory_path,
-      base::Bind(&DrivePrefetcher::OnReadDirectory,
-                 weak_ptr_factory_.GetWeakPtr(),
-                 directory_path));
-}
-
-void DrivePrefetcher::OnReadDirectory(
-    const base::FilePath& directory_path,
-    FileError error,
-    bool hide_hosted_documents,
-    scoped_ptr<DriveEntryProtoVector> entries) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-
-  if (error != FILE_ERROR_OK) {
-    LOG(WARNING) << "Directory cannot be scanned by prefetcher: "
-                 << directory_path.value();
-    OnReadDirectoryFinished();
-    return;
-  }
-
-  // TODO(kinaba): if entries->size() is so big and it does not contain any
-  // directories, the loop below may run on UI thread long time. Consider
-  // splitting it into a smaller asynchronous tasks.
-  for (size_t i = 0; i < entries->size(); ++i) {
-    const DriveEntryProto& entry = (*entries)[i];
-
-    if (entry.file_info().is_directory()) {
-      VisitDirectory(directory_path.Append(entry.base_name()));
-    } else if (entry.has_file_specific_info() &&
-               !entry.file_specific_info().is_hosted_document()) {
-      VisitFile(entry);
-    }
-  }
-
-  OnReadDirectoryFinished();
-}
-
-void DrivePrefetcher::OnReadDirectoryFinished() {
-  DCHECK(number_of_inflight_traversals_ > 0);
-
-  --number_of_inflight_traversals_;
-  if (number_of_inflight_traversals_ == 0)
-    DoPrefetch();  // Start prefetching.
-}
-
-}  // namespace drive