Reduce the memory usage of bookmarks storage

components/bookmarks/browser/bookmark_codec.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_codec.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <utility>
 
 #include "base/json/json_string_value_serializer.h"
 #include "base/memory/ptr_util.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
+#include "base/sys_info.h"
 #include "base/values.h"
 #include "components/bookmarks/browser/bookmark_model.h"
 #include "components/strings/grit/components_strings.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "url/gurl.h"
 
 using base::Time;
 
 namespace bookmarks {
 
@@ skipping 400 matching lines @@
   }
 
   return true;
 }
 
 void BookmarkCodec::DecodeMetaInfoHelper(
     const base::DictionaryValue& dict,
     const std::string& prefix,
     BookmarkNode::MetaInfoMap* meta_info_map) {
   for (base::DictionaryValue::Iterator it(dict); !it.IsAtEnd(); it.Advance()) {
+    // Do not load the image and page data into memory for low-end devices.
+    if (base::SysInfo::IsLowEndDevice() &&

[sky, 2017/05/12 20:00:13]

If we're going to support disabling this feature I would rather the disabling is
explicit rather than keying off IsLowEndDevice. Similarly, the set of keys that
are not needed should be passed in, not hard coded here.

[ssid, 2017/05/25 00:27:27]

So, I moved the strings to storage.cc and passed it as argument to this class
when needed. Do you mean I should disable these meta info for all platforms and
all types of devices instead of just low-end devices?
Sorry I did not fully understand your comment.

+        (it.key().find("imageData") != std::string::npos ||
+         it.key().find("pageData") != std::string::npos)) {
+      continue;
+    }
+
     if (it.value().IsType(base::Value::Type::DICTIONARY)) {
       const base::DictionaryValue* subdict;
       it.value().GetAsDictionary(&subdict);
       DecodeMetaInfoHelper(*subdict, prefix + it.key() + ".", meta_info_map);
     } else if (it.value().IsType(base::Value::Type::STRING)) {
       it.value().GetAsString(&(*meta_info_map)[prefix + it.key()]);
     }
   }
 }
 
@@ skipping 46 matching lines @@
   base::MD5Init(&md5_context_);
 }
 
 void BookmarkCodec::FinalizeChecksum() {
   base::MD5Digest digest;
   base::MD5Final(&digest, &md5_context_);
   computed_checksum_ = base::MD5DigestToBase16(digest);
 }
 
 }  // namespace bookmarks