gdata: Move GDataWapiFeedParser to a set of new files

This change reduces ~400 lines from gdata_file_system.cc

BUG=130669
TEST=none; just move code around. should not change the behaviors
TBR=ben@chromium.org
for chrome_browser.gypi

Review URL: https://chromiumcodereview.appspot.com/10829118

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@149462 0039d316-1c4b-4281-b951-d872f2087c98

5 files changed, 447 insertions, 391 deletions

diff --git a/chrome/browser/chromeos/gdata/gdata_file_system.cc b/chrome/browser/chromeos/gdata/gdata_file_system.cc
index b43da66..a13efb2 100644
--- a/chrome/browser/chromeos/gdata/gdata_file_system.cc
+++ b/chrome/browser/chromeos/gdata/gdata_file_system.cc
@@ -137,23 +137,6 @@ GDataFileError GDataToGDataFileError(GDataErrorCode status) {
 
 //================================ Helper functions ============================
 
-// Recursively extracts the paths set of all sub-directories of |entry|.
-void GetChildDirectoryPaths(GDataEntry* entry,
-                            std::set<FilePath>* changed_dirs) {
-  GDataDirectory* dir = entry->AsGDataDirectory();
-  if (!dir)
-    return;
-
-  for (GDataDirectoryCollection::const_iterator it =
-       dir->child_directories().begin();
-       it != dir->child_directories().end(); ++it) {
-    GDataDirectory* child_dir = it->second;
-    changed_dirs->insert(child_dir->GetFilePath());
-    GetChildDirectoryPaths(child_dir, changed_dirs);
-  }
-}
-
-
 // Invoked upon completion of TransferRegularFile initiated by Copy.
 //
 // |callback| is run on the thread represented by |relay_proxy|.
@@ -575,95 +558,6 @@ void RunGetEntryInfoWithFilePathCallback(
 
 }  // namespace
 
-// Struct used to record UMA stats with FeedToFileResourceMap().
-//
-// TODO(satorux): Move this to a new file. crbug.com/130669
-struct FeedToFileResourceMapUmaStats {
-  FeedToFileResourceMapUmaStats()
-      : num_regular_files(0),
-        num_hosted_documents(0) {}
-
-  typedef std::map<DocumentEntry::EntryKind, int> EntryKindToCountMap;
-  int num_regular_files;
-  int num_hosted_documents;
-  EntryKindToCountMap num_files_with_entry_kind;
-};
-
-// GDataWapiFeedProcessor is used to process feeds from WAPI (codename for
-// Documents List API).
-//
-// TODO(satorux): Move this into a new file. crbug.com/130669
-class GDataWapiFeedProcessor {
- public:
-  explicit GDataWapiFeedProcessor(GDataDirectoryService* directory_service)
-      : directory_service_(directory_service) {
-  }
-
-  // Applies the documents feeds to the file system using |directory_service_|.
-  //
-  // |start_changestamp| determines the type of feed to process. The value is
-  // set to zero for the root feeds, every other value is for the delta feeds.
-  //
-  // In the case of processing the root feeds |root_feed_changestamp| is used
-  // as its initial changestamp value. The value comes from
-  // AccountMetadataFeed.
-  GDataFileError ApplyFeeds(const std::vector<DocumentFeed*>& feed_list,
-                            int start_changestamp,
-                            int root_feed_changestamp,
-                            std::set<FilePath>* changed_dirs);
-
-  // Converts list of document feeds from collected feeds into
-  // FileResourceIdMap.
-  GDataFileError FeedToFileResourceMap(
-    const std::vector<DocumentFeed*>& feed_list,
-    FileResourceIdMap* file_map,
-    int* feed_changestamp,
-    FeedToFileResourceMapUmaStats* uma_stats);
-
- private:
-  // Updates UMA histograms about file counts.
-  void UpdateFileCountUmaHistograms(
-      const FeedToFileResourceMapUmaStats& uma_stats) const;
-
-  // Applies the pre-processed feed from |file_map| map onto the file system.
-  // All entries in |file_map| will be erased (i.e. the map becomes empty),
-  // and values are deleted.
-  void ApplyFeedFromFileUrlMap(bool is_delta_feed,
-                               int feed_changestamp,
-                               FileResourceIdMap* file_map,
-                               std::set<FilePath>* changed_dirs);
-
-  // Helper function for adding new |file| from the feed into |directory|. It
-  // checks the type of file and updates |changed_dirs| if this file adding
-  // operation needs to raise directory notification update. If file is being
-  // added to |orphaned_dir_service| such notifications are not raised since
-  // we ignore such files and don't add them to the file system now.
-  static void AddEntryToDirectoryAndCollectChangedDirectories(
-      GDataEntry* entry,
-      GDataDirectory* directory,
-      GDataDirectoryService* orphaned_dir_service,
-      std::set<FilePath>* changed_dirs);
-
-  // Helper function for removing |entry| from |directory|. If |entry| is a
-  // directory too, it will collect all its children file paths into
-  // |changed_dirs| as well.
-  static void RemoveEntryFromDirectoryAndCollectChangedDirectories(
-      GDataDirectory* directory,
-      GDataEntry* entry,
-      std::set<FilePath>* changed_dirs);
-
-  // Finds directory where new |file| should be added to during feed processing.
-  // |orphaned_entries_dir| collects files/dirs that don't have a parent in
-  // either locally cached file system or in this new feed.
-  GDataDirectory* FindDirectoryForNewEntry(
-      GDataEntry* new_entry,
-      const FileResourceIdMap& file_map,
-      GDataDirectoryService* orphaned_dir_service);
-
-  GDataDirectoryService* directory_service_;
-  DISALLOW_COPY_AND_ASSIGN(GDataWapiFeedProcessor);
-};
-
 // GDataFileSystem::GetDocumentsParams struct implementation.
 struct GDataFileSystem::GetDocumentsParams {
   GetDocumentsParams(int start_changestamp,
@@ -3391,179 +3285,6 @@ GDataFileError GDataFileSystem::UpdateFromFeed(
   return error;
 }
 
-GDataFileError GDataWapiFeedProcessor::ApplyFeeds(
-    const std::vector<DocumentFeed*>& feed_list,
-    int start_changestamp,
-    int root_feed_changestamp,
-    std::set<FilePath>* changed_dirs) {
-  bool is_delta_feed = start_changestamp != 0;
-
-  directory_service_->set_origin(FROM_SERVER);
-
-  int delta_feed_changestamp = 0;
-  FeedToFileResourceMapUmaStats uma_stats;
-  FileResourceIdMap file_map;
-  GDataFileError error = FeedToFileResourceMap(feed_list,
-                                               &file_map,
-                                               &delta_feed_changestamp,
-                                               &uma_stats);
-  if (error != GDATA_FILE_OK)
-    return error;
-
-  ApplyFeedFromFileUrlMap(
-      is_delta_feed,
-      is_delta_feed ? delta_feed_changestamp : root_feed_changestamp,
-      &file_map,
-      changed_dirs);
-
-  // Shouldn't record histograms when processing delta feeds.
-  if (!is_delta_feed)
-    UpdateFileCountUmaHistograms(uma_stats);
-
-  return GDATA_FILE_OK;
-}
-
-void GDataWapiFeedProcessor::UpdateFileCountUmaHistograms(
-    const FeedToFileResourceMapUmaStats& uma_stats) const {
-  const int num_total_files =
-      uma_stats.num_hosted_documents + uma_stats.num_regular_files;
-  UMA_HISTOGRAM_COUNTS("GData.NumberOfRegularFiles",
-                       uma_stats.num_regular_files);
-  UMA_HISTOGRAM_COUNTS("GData.NumberOfHostedDocuments",
-                       uma_stats.num_hosted_documents);
-  UMA_HISTOGRAM_COUNTS("GData.NumberOfTotalFiles", num_total_files);
-  const std::vector<int> all_entry_kinds = DocumentEntry::GetAllEntryKinds();
-  for (FeedToFileResourceMapUmaStats::EntryKindToCountMap::const_iterator iter =
-           uma_stats.num_files_with_entry_kind.begin();
-       iter != uma_stats.num_files_with_entry_kind.end();
-       ++iter) {
-    const DocumentEntry::EntryKind kind = iter->first;
-    const int count = iter->second;
-    for (int i = 0; i < count; ++i) {
-      UMA_HISTOGRAM_CUSTOM_ENUMERATION(
-          "GData.EntryKind", kind, all_entry_kinds);
-    }
-  }
-}
-
-void GDataWapiFeedProcessor::ApplyFeedFromFileUrlMap(
-    bool is_delta_feed,
-    int feed_changestamp,
-    FileResourceIdMap* file_map,
-  std::set<FilePath>* changed_dirs) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-  DCHECK(changed_dirs);
-
-  if (!is_delta_feed) {  // Full update.
-    directory_service_->root()->RemoveChildren();
-    changed_dirs->insert(directory_service_->root()->GetFilePath());
-  }
-  directory_service_->set_largest_changestamp(feed_changestamp);
-
-  scoped_ptr<GDataDirectoryService> orphaned_dir_service(
-      new GDataDirectoryService);
-  // Go through all entries generated by the feed and apply them to the local
-  // snapshot of the file system.
-  for (FileResourceIdMap::iterator it = file_map->begin();
-       it != file_map->end();) {
-    // Ensure that the entry is deleted, unless the ownership is explicitly
-    // transferred by entry.release().
-    scoped_ptr<GDataEntry> entry(it->second);
-    DCHECK_EQ(it->first, entry->resource_id());
-    // Erase the entry so the deleted entry won't be referenced.
-    file_map->erase(it++);
-
-    GDataEntry* old_entry =
-        directory_service_->GetEntryByResourceId(entry->resource_id());
-    GDataDirectory* dest_dir = NULL;
-    if (entry->is_deleted()) {  // Deleted file/directory.
-      DVLOG(1) << "Removing file " << entry->base_name();
-      if (!old_entry)
-        continue;
-
-      dest_dir = old_entry->parent();
-      if (!dest_dir) {
-        NOTREACHED();
-        continue;
-      }
-      RemoveEntryFromDirectoryAndCollectChangedDirectories(
-          dest_dir, old_entry, changed_dirs);
-    } else if (old_entry) {  // Change or move of existing entry.
-      // Please note that entry rename is just a special case of change here
-      // since name is just one of the properties that can change.
-      DVLOG(1) << "Changed file " << entry->base_name();
-      dest_dir = old_entry->parent();
-      if (!dest_dir) {
-        NOTREACHED();
-        continue;
-      }
-      // Move children files over if we are dealing with directories.
-      if (old_entry->AsGDataDirectory() && entry->AsGDataDirectory()) {
-        entry->AsGDataDirectory()->TakeOverEntries(
-            old_entry->AsGDataDirectory());
-      }
-      // Remove the old instance of this entry.
-      RemoveEntryFromDirectoryAndCollectChangedDirectories(
-          dest_dir, old_entry, changed_dirs);
-      // Did we actually move the new file to another directory?
-      if (dest_dir->resource_id() != entry->parent_resource_id()) {
-        changed_dirs->insert(dest_dir->GetFilePath());
-        dest_dir = FindDirectoryForNewEntry(entry.get(),
-                                            *file_map,
-                                            orphaned_dir_service.get());
-      }
-      DCHECK(dest_dir);
-      AddEntryToDirectoryAndCollectChangedDirectories(
-          entry.release(),
-          dest_dir,
-          orphaned_dir_service.get(),
-          changed_dirs);
-    } else {  // Adding a new file.
-      dest_dir = FindDirectoryForNewEntry(entry.get(),
-                                          *file_map,
-                                          orphaned_dir_service.get());
-      DCHECK(dest_dir);
-      AddEntryToDirectoryAndCollectChangedDirectories(
-          entry.release(),
-          dest_dir,
-          orphaned_dir_service.get(),
-          changed_dirs);
-    }
-
-    // Record changed directory if this was a delta feed and the parent
-    // directory is already properly rooted within its parent.
-    if (dest_dir && (dest_dir->parent() ||
-        dest_dir == directory_service_->root()) &&
-        dest_dir != orphaned_dir_service->root() && is_delta_feed) {
-      changed_dirs->insert(dest_dir->GetFilePath());
-    }
-  }
-  // All entry must be erased from the map.
-  DCHECK(file_map->empty());
-}
-
-// static
-void GDataWapiFeedProcessor::AddEntryToDirectoryAndCollectChangedDirectories(
-    GDataEntry* entry,
-    GDataDirectory* directory,
-    GDataDirectoryService* orphaned_dir_service,
-    std::set<FilePath>* changed_dirs) {
-  directory->AddEntry(entry);
-  if (entry->AsGDataDirectory() && directory != orphaned_dir_service->root())
-    changed_dirs->insert(entry->GetFilePath());
-}
-
-// static
-void GDataWapiFeedProcessor::
-RemoveEntryFromDirectoryAndCollectChangedDirectories(
-    GDataDirectory* directory,
-    GDataEntry* entry,
-    std::set<FilePath>* changed_dirs) {
-  // Get the list of all sub-directory paths, so we can notify their listeners
-  // that they are smoked.
-  GetChildDirectoryPaths(entry, changed_dirs);
-  directory->RemoveEntry(entry);
-}
 
 // static
 void GDataFileSystem::RemoveStaleEntryOnUpload(const std::string& resource_id,
@@ -3578,113 +3299,6 @@ void GDataFileSystem::RemoveStaleEntryOnUpload(const std::string& resource_id,
   }
 }
 
-GDataDirectory* GDataWapiFeedProcessor::FindDirectoryForNewEntry(
-    GDataEntry* new_entry,
-    const FileResourceIdMap& file_map,
-    GDataDirectoryService* orphaned_dir_service) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-  GDataDirectory* dir = NULL;
-  // Added file.
-  const std::string& parent_id = new_entry->parent_resource_id();
-  if (parent_id.empty()) {
-    dir = directory_service_->root();
-    DVLOG(1) << "Root parent for " << new_entry->base_name();
-  } else {
-    GDataEntry* entry = directory_service_->GetEntryByResourceId(parent_id);
-    dir = entry ? entry->AsGDataDirectory() : NULL;
-    if (!dir) {
-      // The parent directory was also added with this set of feeds.
-      FileResourceIdMap::const_iterator find_iter =
-          file_map.find(parent_id);
-      dir = (find_iter != file_map.end() &&
-             find_iter->second) ?
-                find_iter->second->AsGDataDirectory() : NULL;
-      if (dir) {
-        DVLOG(1) << "Found parent for " << new_entry->base_name()
-                 << " in file_map " << parent_id;
-      } else {
-        DVLOG(1) << "Adding orphan " << new_entry->GetFilePath().value();
-        dir = orphaned_dir_service->root();
-      }
-    }
-  }
-  return dir;
-}
-
-GDataFileError GDataWapiFeedProcessor::FeedToFileResourceMap(
-    const std::vector<DocumentFeed*>& feed_list,
-    FileResourceIdMap* file_map,
-    int* feed_changestamp,
-    FeedToFileResourceMapUmaStats* uma_stats) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-  DCHECK(uma_stats);
-
-  GDataFileError error = GDATA_FILE_OK;
-  uma_stats->num_regular_files = 0;
-  uma_stats->num_hosted_documents = 0;
-  uma_stats->num_files_with_entry_kind.clear();
-  for (size_t i = 0; i < feed_list.size(); ++i) {
-    const DocumentFeed* feed = feed_list[i];
-
-    // Get upload url from the root feed. Links for all other collections will
-    // be handled in GDatadirectory::FromDocumentEntry();
-    if (i == 0) {
-      const Link* root_feed_upload_link =
-          feed->GetLinkByType(Link::RESUMABLE_CREATE_MEDIA);
-      if (root_feed_upload_link)
-        directory_service_->root()->set_upload_url(
-            root_feed_upload_link->href());
-      *feed_changestamp = feed->largest_changestamp();
-      DCHECK_GE(*feed_changestamp, 0);
-    }
-
-    for (ScopedVector<DocumentEntry>::const_iterator iter =
-             feed->entries().begin();
-         iter != feed->entries().end(); ++iter) {
-      DocumentEntry* doc = *iter;
-      GDataEntry* entry = GDataEntry::FromDocumentEntry(
-          NULL, doc, directory_service_);
-      // Some document entries don't map into files (i.e. sites).
-      if (!entry)
-        continue;
-      // Count the number of files.
-      GDataFile* as_file = entry->AsGDataFile();
-      if (as_file) {
-        if (as_file->is_hosted_document())
-          ++uma_stats->num_hosted_documents;
-        else
-          ++uma_stats->num_regular_files;
-        ++uma_stats->num_files_with_entry_kind[as_file->kind()];
-      }
-
-      FileResourceIdMap::iterator map_entry =
-          file_map->find(entry->resource_id());
-
-      // An entry with the same self link may already exist, so we need to
-      // release the existing GDataEntry instance before overwriting the
-      // entry with another GDataEntry instance.
-      if (map_entry != file_map->end()) {
-        LOG(WARNING) << "Found duplicate file "
-                     << map_entry->second->base_name();
-
-        delete map_entry->second;
-        file_map->erase(map_entry);
-      }
-      file_map->insert(
-          std::pair<std::string, GDataEntry*>(entry->resource_id(), entry));
-    }
-  }
-
-  if (error != GDATA_FILE_OK) {
-    // If the code above fails to parse a feed, any GDataEntry instance
-    // added to |file_by_url| is not managed by a GDataDirectory instance,
-    // so we need to explicitly release them here.
-    STLDeleteValues(file_map);
-  }
-
-  return error;
-}
-
 void GDataFileSystem::NotifyDirectoryChanged(const FilePath& directory_path) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
diff --git a/chrome/browser/chromeos/gdata/gdata_file_system.h b/chrome/browser/chromeos/gdata/gdata_file_system.h
index 705dacc..f4d3719 100644
--- a/chrome/browser/chromeos/gdata/gdata_file_system.h
+++ b/chrome/browser/chromeos/gdata/gdata_file_system.h
@@ -19,6 +19,7 @@
 #include "chrome/browser/chromeos/gdata/gdata_file_system_interface.h"
 #include "chrome/browser/chromeos/gdata/gdata_errorcode.h"
 #include "chrome/browser/chromeos/gdata/gdata_files.h"
+#include "chrome/browser/chromeos/gdata/gdata_wapi_feed_processor.h"
 #include "chrome/browser/prefs/pref_change_registrar.h"
 #include "content/public/browser/notification_observer.h"
 
@@ -38,10 +39,6 @@ namespace {
 struct LoadRootFeedParams;
 }  // namespace
 
-// TODO(satorux): Move this into a new file. crbug.com/130669
-typedef std::map<std::string /* resource_id */, GDataEntry*>
-    FileResourceIdMap;
-
 // The production implementation of GDataFileSystemInterface.
 class GDataFileSystem : public GDataFileSystemInterface,
                         public content::NotificationObserver {
@@ -799,7 +796,8 @@ class GDataFileSystem : public GDataFileSystemInterface,
       const FilePath& file_path);
   void OnRequestDirectoryRefresh(GetDocumentsParams* params,
                                  GDataFileError error);
-  void RequestDirectoryRefreshByEntry(const FilePath& directory_path,
+  void RequestDirectoryRefreshByEntry(
+      const FilePath& directory_path,
       const std::string& directory_resource_id,
       const FileResourceIdMap& file_map,
       GDataEntry* directory_entry);
diff --git a/chrome/browser/chromeos/gdata/gdata_wapi_feed_processor.cc b/chrome/browser/chromeos/gdata/gdata_wapi_feed_processor.cc
new file mode 100644
index 0000000..b349f93
--- /dev/null
+++ b/chrome/browser/chromeos/gdata/gdata_wapi_feed_processor.cc
@@ -0,0 +1,331 @@
+// 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 "base/metrics/histogram.h"
+#include "chrome/browser/chromeos/gdata/gdata_files.h"
+#include "chrome/browser/chromeos/gdata/gdata_wapi_feed_processor.h"
+#include "content/public/browser/browser_thread.h"
+
+using content::BrowserThread;
+
+namespace gdata {
+
+namespace {
+
+// Recursively extracts the paths set of all sub-directories of |entry|.
+void GetChildDirectoryPaths(GDataEntry* entry,
+                            std::set<FilePath>* changed_dirs) {
+  GDataDirectory* dir = entry->AsGDataDirectory();
+  if (!dir)
+    return;
+
+  for (GDataDirectoryCollection::const_iterator it =
+       dir->child_directories().begin();
+       it != dir->child_directories().end(); ++it) {
+    GDataDirectory* child_dir = it->second;
+    changed_dirs->insert(child_dir->GetFilePath());
+    GetChildDirectoryPaths(child_dir, changed_dirs);
+  }
+}
+
+}  // namespace
+
+FeedToFileResourceMapUmaStats::FeedToFileResourceMapUmaStats()
+    : num_regular_files(0),
+      num_hosted_documents(0) {
+}
+
+FeedToFileResourceMapUmaStats::~FeedToFileResourceMapUmaStats() {
+}
+
+GDataWapiFeedProcessor::GDataWapiFeedProcessor(
+    GDataDirectoryService* directory_service)
+  : directory_service_(directory_service) {
+}
+
+GDataWapiFeedProcessor::~GDataWapiFeedProcessor() {
+}
+
+GDataFileError GDataWapiFeedProcessor::ApplyFeeds(
+    const std::vector<DocumentFeed*>& feed_list,
+    int start_changestamp,
+    int root_feed_changestamp,
+    std::set<FilePath>* changed_dirs) {
+  bool is_delta_feed = start_changestamp != 0;
+
+  directory_service_->set_origin(FROM_SERVER);
+
+  int delta_feed_changestamp = 0;
+  FeedToFileResourceMapUmaStats uma_stats;
+  FileResourceIdMap file_map;
+  GDataFileError error = FeedToFileResourceMap(feed_list,
+                                               &file_map,
+                                               &delta_feed_changestamp,
+                                               &uma_stats);
+  if (error != GDATA_FILE_OK)
+    return error;
+
+  ApplyFeedFromFileUrlMap(
+      is_delta_feed,
+      is_delta_feed ? delta_feed_changestamp : root_feed_changestamp,
+      &file_map,
+      changed_dirs);
+
+  // Shouldn't record histograms when processing delta feeds.
+  if (!is_delta_feed)
+    UpdateFileCountUmaHistograms(uma_stats);
+
+  return GDATA_FILE_OK;
+}
+
+void GDataWapiFeedProcessor::UpdateFileCountUmaHistograms(
+    const FeedToFileResourceMapUmaStats& uma_stats) const {
+  const int num_total_files =
+      uma_stats.num_hosted_documents + uma_stats.num_regular_files;
+  UMA_HISTOGRAM_COUNTS("GData.NumberOfRegularFiles",
+                       uma_stats.num_regular_files);
+  UMA_HISTOGRAM_COUNTS("GData.NumberOfHostedDocuments",
+                       uma_stats.num_hosted_documents);
+  UMA_HISTOGRAM_COUNTS("GData.NumberOfTotalFiles", num_total_files);
+  const std::vector<int> all_entry_kinds = DocumentEntry::GetAllEntryKinds();
+  for (FeedToFileResourceMapUmaStats::EntryKindToCountMap::const_iterator iter =
+           uma_stats.num_files_with_entry_kind.begin();
+       iter != uma_stats.num_files_with_entry_kind.end();
+       ++iter) {
+    const DocumentEntry::EntryKind kind = iter->first;
+    const int count = iter->second;
+    for (int i = 0; i < count; ++i) {
+      UMA_HISTOGRAM_CUSTOM_ENUMERATION(
+          "GData.EntryKind", kind, all_entry_kinds);
+    }
+  }
+}
+
+void GDataWapiFeedProcessor::ApplyFeedFromFileUrlMap(
+    bool is_delta_feed,
+    int feed_changestamp,
+    FileResourceIdMap* file_map,
+  std::set<FilePath>* changed_dirs) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  DCHECK(changed_dirs);
+
+  if (!is_delta_feed) {  // Full update.
+    directory_service_->root()->RemoveChildren();
+    changed_dirs->insert(directory_service_->root()->GetFilePath());
+  }
+  directory_service_->set_largest_changestamp(feed_changestamp);
+
+  scoped_ptr<GDataDirectoryService> orphaned_dir_service(
+      new GDataDirectoryService);
+  // Go through all entries generated by the feed and apply them to the local
+  // snapshot of the file system.
+  for (FileResourceIdMap::iterator it = file_map->begin();
+       it != file_map->end();) {
+    // Ensure that the entry is deleted, unless the ownership is explicitly
+    // transferred by entry.release().
+    scoped_ptr<GDataEntry> entry(it->second);
+    DCHECK_EQ(it->first, entry->resource_id());
+    // Erase the entry so the deleted entry won't be referenced.
+    file_map->erase(it++);
+
+    GDataEntry* old_entry =
+        directory_service_->GetEntryByResourceId(entry->resource_id());
+    GDataDirectory* dest_dir = NULL;
+    if (entry->is_deleted()) {  // Deleted file/directory.
+      DVLOG(1) << "Removing file " << entry->base_name();
+      if (!old_entry)
+        continue;
+
+      dest_dir = old_entry->parent();
+      if (!dest_dir) {
+        NOTREACHED();
+        continue;
+      }
+      RemoveEntryFromDirectoryAndCollectChangedDirectories(
+          dest_dir, old_entry, changed_dirs);
+    } else if (old_entry) {  // Change or move of existing entry.
+      // Please note that entry rename is just a special case of change here
+      // since name is just one of the properties that can change.
+      DVLOG(1) << "Changed file " << entry->base_name();
+      dest_dir = old_entry->parent();
+      if (!dest_dir) {
+        NOTREACHED();
+        continue;
+      }
+      // Move children files over if we are dealing with directories.
+      if (old_entry->AsGDataDirectory() && entry->AsGDataDirectory()) {
+        entry->AsGDataDirectory()->TakeOverEntries(
+            old_entry->AsGDataDirectory());
+      }
+      // Remove the old instance of this entry.
+      RemoveEntryFromDirectoryAndCollectChangedDirectories(
+          dest_dir, old_entry, changed_dirs);
+      // Did we actually move the new file to another directory?
+      if (dest_dir->resource_id() != entry->parent_resource_id()) {
+        changed_dirs->insert(dest_dir->GetFilePath());
+        dest_dir = FindDirectoryForNewEntry(entry.get(),
+                                            *file_map,
+                                            orphaned_dir_service.get());
+      }
+      DCHECK(dest_dir);
+      AddEntryToDirectoryAndCollectChangedDirectories(
+          entry.release(),
+          dest_dir,
+          orphaned_dir_service.get(),
+          changed_dirs);
+    } else {  // Adding a new file.
+      dest_dir = FindDirectoryForNewEntry(entry.get(),
+                                          *file_map,
+                                          orphaned_dir_service.get());
+      DCHECK(dest_dir);
+      AddEntryToDirectoryAndCollectChangedDirectories(
+          entry.release(),
+          dest_dir,
+          orphaned_dir_service.get(),
+          changed_dirs);
+    }
+
+    // Record changed directory if this was a delta feed and the parent
+    // directory is already properly rooted within its parent.
+    if (dest_dir && (dest_dir->parent() ||
+        dest_dir == directory_service_->root()) &&
+        dest_dir != orphaned_dir_service->root() && is_delta_feed) {
+      changed_dirs->insert(dest_dir->GetFilePath());
+    }
+  }
+  // All entry must be erased from the map.
+  DCHECK(file_map->empty());
+}
+
+// static
+void GDataWapiFeedProcessor::AddEntryToDirectoryAndCollectChangedDirectories(
+    GDataEntry* entry,
+    GDataDirectory* directory,
+    GDataDirectoryService* orphaned_dir_service,
+    std::set<FilePath>* changed_dirs) {
+  directory->AddEntry(entry);
+  if (entry->AsGDataDirectory() && directory != orphaned_dir_service->root())
+    changed_dirs->insert(entry->GetFilePath());
+}
+
+// static
+void GDataWapiFeedProcessor::
+RemoveEntryFromDirectoryAndCollectChangedDirectories(
+    GDataDirectory* directory,
+    GDataEntry* entry,
+    std::set<FilePath>* changed_dirs) {
+  // Get the list of all sub-directory paths, so we can notify their listeners
+  // that they are smoked.
+  GetChildDirectoryPaths(entry, changed_dirs);
+  directory->RemoveEntry(entry);
+}
+
+GDataDirectory* GDataWapiFeedProcessor::FindDirectoryForNewEntry(
+    GDataEntry* new_entry,
+    const FileResourceIdMap& file_map,
+    GDataDirectoryService* orphaned_dir_service) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  GDataDirectory* dir = NULL;
+  // Added file.
+  const std::string& parent_id = new_entry->parent_resource_id();
+  if (parent_id.empty()) {
+    dir = directory_service_->root();
+    DVLOG(1) << "Root parent for " << new_entry->base_name();
+  } else {
+    GDataEntry* entry = directory_service_->GetEntryByResourceId(parent_id);
+    dir = entry ? entry->AsGDataDirectory() : NULL;
+    if (!dir) {
+      // The parent directory was also added with this set of feeds.
+      FileResourceIdMap::const_iterator find_iter =
+          file_map.find(parent_id);
+      dir = (find_iter != file_map.end() &&
+             find_iter->second) ?
+                find_iter->second->AsGDataDirectory() : NULL;
+      if (dir) {
+        DVLOG(1) << "Found parent for " << new_entry->base_name()
+                 << " in file_map " << parent_id;
+      } else {
+        DVLOG(1) << "Adding orphan " << new_entry->GetFilePath().value();
+        dir = orphaned_dir_service->root();
+      }
+    }
+  }
+  return dir;
+}
+
+GDataFileError GDataWapiFeedProcessor::FeedToFileResourceMap(
+    const std::vector<DocumentFeed*>& feed_list,
+    FileResourceIdMap* file_map,
+    int* feed_changestamp,
+    FeedToFileResourceMapUmaStats* uma_stats) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  DCHECK(uma_stats);
+
+  GDataFileError error = GDATA_FILE_OK;
+  uma_stats->num_regular_files = 0;
+  uma_stats->num_hosted_documents = 0;
+  uma_stats->num_files_with_entry_kind.clear();
+  for (size_t i = 0; i < feed_list.size(); ++i) {
+    const DocumentFeed* feed = feed_list[i];
+
+    // Get upload url from the root feed. Links for all other collections will
+    // be handled in GDatadirectory::FromDocumentEntry();
+    if (i == 0) {
+      const Link* root_feed_upload_link =
+          feed->GetLinkByType(Link::RESUMABLE_CREATE_MEDIA);
+      if (root_feed_upload_link)
+        directory_service_->root()->set_upload_url(
+            root_feed_upload_link->href());
+      *feed_changestamp = feed->largest_changestamp();
+      DCHECK_GE(*feed_changestamp, 0);
+    }
+
+    for (ScopedVector<DocumentEntry>::const_iterator iter =
+             feed->entries().begin();
+         iter != feed->entries().end(); ++iter) {
+      DocumentEntry* doc = *iter;
+      GDataEntry* entry = GDataEntry::FromDocumentEntry(
+          NULL, doc, directory_service_);
+      // Some document entries don't map into files (i.e. sites).
+      if (!entry)
+        continue;
+      // Count the number of files.
+      GDataFile* as_file = entry->AsGDataFile();
+      if (as_file) {
+        if (as_file->is_hosted_document())
+          ++uma_stats->num_hosted_documents;
+        else
+          ++uma_stats->num_regular_files;
+        ++uma_stats->num_files_with_entry_kind[as_file->kind()];
+      }
+
+      FileResourceIdMap::iterator map_entry =
+          file_map->find(entry->resource_id());
+
+      // An entry with the same self link may already exist, so we need to
+      // release the existing GDataEntry instance before overwriting the
+      // entry with another GDataEntry instance.
+      if (map_entry != file_map->end()) {
+        LOG(WARNING) << "Found duplicate file "
+                     << map_entry->second->base_name();
+
+        delete map_entry->second;
+        file_map->erase(map_entry);
+      }
+      file_map->insert(
+          std::pair<std::string, GDataEntry*>(entry->resource_id(), entry));
+    }
+  }
+
+  if (error != GDATA_FILE_OK) {
+    // If the code above fails to parse a feed, any GDataEntry instance
+    // added to |file_by_url| is not managed by a GDataDirectory instance,
+    // so we need to explicitly release them here.
+    STLDeleteValues(file_map);
+  }
+
+  return error;
+}
+
+}  // namespace gdata
diff --git a/chrome/browser/chromeos/gdata/gdata_wapi_feed_processor.h b/chrome/browser/chromeos/gdata/gdata_wapi_feed_processor.h
new file mode 100644
index 0000000..9bb8465
--- /dev/null
+++ b/chrome/browser/chromeos/gdata/gdata_wapi_feed_processor.h
@@ -0,0 +1,111 @@
+// 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_GDATA_GDATA_WAPI_FEED_PROCESSOR_H_
+#define CHROME_BROWSER_CHROMEOS_GDATA_GDATA_WAPI_FEED_PROCESSOR_H_
+
+#include <map>
+#include <set>
+#include <string>
+#include <vector>
+
+#include "base/file_path.h"
+#include "chrome/browser/chromeos/gdata/gdata_errorcode.h"
+#include "chrome/browser/chromeos/gdata/gdata_wapi_parser.h"
+
+namespace gdata {
+
+class GDataDirectory;
+class GDataDirectoryService;
+class GDataEntry;
+
+typedef std::map<std::string /* resource_id */, GDataEntry*>
+FileResourceIdMap;
+
+// Struct used to record UMA stats with FeedToFileResourceMap().
+struct FeedToFileResourceMapUmaStats {
+  FeedToFileResourceMapUmaStats();
+  ~FeedToFileResourceMapUmaStats();
+
+  typedef std::map<DocumentEntry::EntryKind, int> EntryKindToCountMap;
+  int num_regular_files;
+  int num_hosted_documents;
+  EntryKindToCountMap num_files_with_entry_kind;
+};
+
+// GDataWapiFeedProcessor is used to process feeds from WAPI (codename for
+// Documents List API).
+class GDataWapiFeedProcessor {
+ public:
+  explicit GDataWapiFeedProcessor(GDataDirectoryService* directory_service);
+  ~GDataWapiFeedProcessor();
+
+  // Applies the documents feeds to the file system using |directory_service_|.
+  //
+  // |start_changestamp| determines the type of feed to process. The value is
+  // set to zero for the root feeds, every other value is for the delta feeds.
+  //
+  // In the case of processing the root feeds |root_feed_changestamp| is used
+  // as its initial changestamp value. The value comes from
+  // AccountMetadataFeed.
+  GDataFileError ApplyFeeds(const std::vector<DocumentFeed*>& feed_list,
+                            int start_changestamp,
+                            int root_feed_changestamp,
+                            std::set<FilePath>* changed_dirs);
+
+  // Converts list of document feeds from collected feeds into
+  // FileResourceIdMap.
+  GDataFileError FeedToFileResourceMap(
+    const std::vector<DocumentFeed*>& feed_list,
+    FileResourceIdMap* file_map,
+    int* feed_changestamp,
+    FeedToFileResourceMapUmaStats* uma_stats);
+
+ private:
+  // Updates UMA histograms about file counts.
+  void UpdateFileCountUmaHistograms(
+      const FeedToFileResourceMapUmaStats& uma_stats) const;
+
+  // Applies the pre-processed feed from |file_map| map onto the file system.
+  // All entries in |file_map| will be erased (i.e. the map becomes empty),
+  // and values are deleted.
+  void ApplyFeedFromFileUrlMap(bool is_delta_feed,
+                               int feed_changestamp,
+                               FileResourceIdMap* file_map,
+                               std::set<FilePath>* changed_dirs);
+
+  // Helper function for adding new |file| from the feed into |directory|. It
+  // checks the type of file and updates |changed_dirs| if this file adding
+  // operation needs to raise directory notification update. If file is being
+  // added to |orphaned_dir_service| such notifications are not raised since
+  // we ignore such files and don't add them to the file system now.
+  static void AddEntryToDirectoryAndCollectChangedDirectories(
+      GDataEntry* entry,
+      GDataDirectory* directory,
+      GDataDirectoryService* orphaned_dir_service,
+      std::set<FilePath>* changed_dirs);
+
+  // Helper function for removing |entry| from |directory|. If |entry| is a
+  // directory too, it will collect all its children file paths into
+  // |changed_dirs| as well.
+  static void RemoveEntryFromDirectoryAndCollectChangedDirectories(
+      GDataDirectory* directory,
+      GDataEntry* entry,
+      std::set<FilePath>* changed_dirs);
+
+  // Finds directory where new |file| should be added to during feed processing.
+  // |orphaned_entries_dir| collects files/dirs that don't have a parent in
+  // either locally cached file system or in this new feed.
+  GDataDirectory* FindDirectoryForNewEntry(
+      GDataEntry* new_entry,
+      const FileResourceIdMap& file_map,
+      GDataDirectoryService* orphaned_dir_service);
+
+  GDataDirectoryService* directory_service_;  // Not owned by the class.
+  DISALLOW_COPY_AND_ASSIGN(GDataWapiFeedProcessor);
+};
+
+}  // namespace gdata
+
+#endif  // CHROME_BROWSER_CHROMEOS_GDATA_GDATA_WAPI_FEED_PROCESSOR_H_
diff --git a/chrome/chrome_browser.gypi b/chrome/chrome_browser.gypi
index b5a0882..c5afe43 100644
--- a/chrome/chrome_browser.gypi
+++ b/chrome/chrome_browser.gypi
@@ -585,6 +585,8 @@
         'browser/chromeos/gdata/gdata_uploader.h',
         'browser/chromeos/gdata/gdata_util.cc',
         'browser/chromeos/gdata/gdata_util.h',
+        'browser/chromeos/gdata/gdata_wapi_feed_processor.cc',
+        'browser/chromeos/gdata/gdata_wapi_feed_processor.h',
         'browser/chromeos/gdata/gdata_wapi_parser.cc',
         'browser/chromeos/gdata/gdata_wapi_parser.h',
         'browser/chromeos/gdata/operations_base.cc',