Reduce the memory usage of bookmarks storage

components/bookmarks/browser/bookmark_storage.cc

 // Copyright 2014 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/bookmarks/browser/bookmark_storage.h"
 
 #include <stddef.h>
 #include <algorithm>
 #include <utility>
 
 #include "base/bind.h"
 #include "base/compiler_specific.h"
 #include "base/files/file_util.h"
 #include "base/json/json_file_value_serializer.h"
 #include "base/json/json_reader.h"
 #include "base/json/json_string_value_serializer.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/sequenced_task_runner.h"
+#include "base/sys_info.h"
 #include "base/time/time.h"
 #include "components/bookmarks/browser/bookmark_codec.h"
 #include "components/bookmarks/browser/bookmark_model.h"
 #include "components/bookmarks/browser/titled_url_index.h"
 #include "components/bookmarks/common/bookmark_constants.h"
 
 using base::TimeTicks;
 
 namespace bookmarks {
 
 namespace {
 
 // Extension used for backup files (copy of main file created during startup).
 const base::FilePath::CharType kBackupExtension[] = FILE_PATH_LITERAL("bak");
 
 // How often we save.
 const int kSaveDelayMS = 2500;
 
+// Optional keys present in MetaInfo maps in bookmark nodes to load in memory.
+const char* const kOptionalMetakeys[] = {"imageData", "pageData"};
+
 void BackupCallback(const base::FilePath& path) {
   base::FilePath backup_path = path.ReplaceExtension(kBackupExtension);
   base::CopyFile(path, backup_path);
 }
 
 // Adds node to the model's index, recursing through all children as well.
 void AddBookmarksToIndex(BookmarkLoadDetails* details,
                          BookmarkNode* node) {
   if (node->is_url()) {
     if (node->url().is_valid())
@@ skipping 15 matching lines @@
     // all bookmarks if some titles have invalid utf.
     JSONFileValueDeserializer deserializer(
         path, base::JSON_REPLACE_INVALID_CHARACTERS);
     std::unique_ptr<base::Value> root = deserializer.Deserialize(NULL, NULL);
 
     if (root.get()) {
       // Building the index can take a while, so we do it on the background
       // thread.
       int64_t max_node_id = 0;
       BookmarkCodec codec;
+      // Do not load the image and page data into memory for low-end devices.
+      if (base::SysInfo::IsLowEndDevice()) {

[sky, 2017/05/25 02:54:03]

What I was getting at with my earlier comment is that rather than hard coding
that low-end-device == ignore certain keys that you pass into BookmarkModel this
information. Basically BookmarkModel (probably via the client interface) has a
way to specify what meta keys should be ignored. It's up to the actual consumer
(by way of the BookmarkClient interface) to specify what those keys are. I'm
saying you add something like std::set<std::string> ExecludedMetaKeys() to the
BookmarkClient interface.

[ssid, 2017/05/26 01:45:40]

I think I have made changes as you suggested.

+        std::list<const char*> optional_keys(std::begin(kOptionalMetakeys),
+                                             std::end(kOptionalMetakeys));
+        codec.set_excluded_meta_info_keys(optional_keys);
+      }
+
       TimeTicks start_time = TimeTicks::Now();
       codec.Decode(details->bb_node(), details->other_folder_node(),
                    details->mobile_folder_node(), &max_node_id, *root.get());
       details->set_max_id(std::max(max_node_id, details->max_id()));
       details->set_computed_checksum(codec.computed_checksum());
       details->set_stored_checksum(codec.stored_checksum());
       details->set_ids_reassigned(codec.ids_reassigned());
       details->set_model_meta_info_map(codec.model_meta_info_map());
       details->set_model_sync_transaction_version(
           codec.model_sync_transaction_version());
@@ skipping 147 matching lines @@
   }
 
   std::unique_ptr<std::string> data(new std::string);
   if (!SerializeData(data.get()))
     return false;
   writer_.WriteNow(std::move(data));
   return true;
 }
 
 }  // namespace bookmarks