Update from https://crrev.com/329939

base/prefs/json_pref_store.h

Index: base/prefs/json_pref_store.h
diff --git a/base/prefs/json_pref_store.h b/base/prefs/json_pref_store.h
index 1badcf2257ca3c3c8e058c4a55fd80e657a5e12d..ef260eb47da00b913918031bd55ed5b80978664a 100644
--- a/base/prefs/json_pref_store.h
+++ b/base/prefs/json_pref_store.h
@@ -29,6 +29,7 @@ class Clock;
 class DictionaryValue;
 class FilePath;
 class HistogramBase;
+class JsonPrefStoreLossyWriteTest;
 class SequencedTaskRunner;
 class SequencedWorkerPool;
 class Value;
@@ -82,9 +83,13 @@ class BASE_PREFS_EXPORT JsonPrefStore
 
   // PersistentPrefStore overrides:
   bool GetMutableValue(const std::string& key, base::Value** result) override;
-  void SetValue(const std::string& key, base::Value* value) override;
-  void SetValueSilently(const std::string& key, base::Value* value) override;
-  void RemoveValue(const std::string& key) override;
+  void SetValue(const std::string& key,
+                base::Value* value,
+                uint32 flags) override;
+  void SetValueSilently(const std::string& key,
+                        base::Value* value,
+                        uint32 flags) override;
+  void RemoveValue(const std::string& key, uint32 flags) override;
   bool ReadOnly() const override;
   PrefReadError GetReadError() const override;
   // Note this method may be asynchronous if this instance has a |pref_filter_|
@@ -93,11 +98,11 @@ class BASE_PREFS_EXPORT JsonPrefStore
   PrefReadError ReadPrefs() override;
   void ReadPrefsAsync(ReadErrorDelegate* error_delegate) override;
   void CommitPendingWrite() override;
-  void ReportValueChanged(const std::string& key) override;
+  void ReportValueChanged(const std::string& key, uint32 flags) override;
 
   // Just like RemoveValue(), but doesn't notify observers. Used when doing some
   // cleanup that shouldn't otherwise alert observers.
-  void RemoveValueSilently(const std::string& key);
+  void RemoveValueSilently(const std::string& key, uint32 flags);
 
   // Registers |on_next_successful_write| to be called once, on the next
   // successful write event of |writer_|.
@@ -161,6 +166,7 @@ class BASE_PREFS_EXPORT JsonPrefStore
                            WriteCountHistogramTestMultiplePeriods);
   FRIEND_TEST_ALL_PREFIXES(base::JsonPrefStoreTest,
                            WriteCountHistogramTestPeriodWithGaps);
+  friend class base::JsonPrefStoreLossyWriteTest;
 
   ~JsonPrefStore() override;
 
@@ -186,6 +192,10 @@ class BASE_PREFS_EXPORT JsonPrefStore
                         scoped_ptr<base::DictionaryValue> prefs,
                         bool schedule_write);
 
+  // Schedule a write with the file writer as long as |flags| doesn't contain
+  // WriteablePrefStore::LOSSY_PREF_WRITE_FLAG.
+  void ScheduleWrite(uint32 flags);
+
   const base::FilePath path_;
   const base::FilePath alternate_path_;
   const scoped_refptr<base::SequencedTaskRunner> sequenced_task_runner_;
@@ -204,6 +214,7 @@ class BASE_PREFS_EXPORT JsonPrefStore
 
   bool initialized_;
   bool filtering_in_progress_;
+  bool pending_lossy_write_;
   PrefReadError read_error_;
 
   std::set<std::string> keys_need_empty_value_;