Reduce the memory usage of bookmarks storage

components/bookmarks/browser/bookmark_storage.cc

Index: components/bookmarks/browser/bookmark_storage.cc
diff --git a/components/bookmarks/browser/bookmark_storage.cc b/components/bookmarks/browser/bookmark_storage.cc
index d32a90c88061a8b082c770da656f63da4bdfc0a2..d7bebde71730f17062c2070d2643af020c6611d8 100644
--- a/components/bookmarks/browser/bookmark_storage.cc
+++ b/components/bookmarks/browser/bookmark_storage.cc
@@ -16,6 +16,7 @@
 #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"
@@ -34,6 +35,9 @@ 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);
@@ -69,6 +73,13 @@ void LoadCallback(const base::FilePath& path,
       // 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());