Add synchronous callback support to important_file_writer.cc

base/files/important_file_writer.cc

Index: base/files/important_file_writer.cc
diff --git a/base/files/important_file_writer.cc b/base/files/important_file_writer.cc
index 28550ad52fc9addfe6c2fdb8f908c069b2647eab..a496285f81803b182dd50e572a3f8c5fd0362541 100644
--- a/base/files/important_file_writer.cc
+++ b/base/files/important_file_writer.cc
@@ -58,8 +58,14 @@ void LogFailure(const FilePath& path, TempFileFailure failure_code,
 // Helper function to call WriteFileAtomically() with a
 // std::unique_ptr<std::string>.
 bool WriteScopedStringToFileAtomically(const FilePath& path,
-                                       std::unique_ptr<std::string> data) {
-  return ImportantFileWriter::WriteFileAtomically(path, *data);
+                                       std::unique_ptr<std::string> data,
+                                       Callback<void(bool success)> callback) {
+  bool result = ImportantFileWriter::WriteFileAtomically(path, *data);
+
+  if (!callback.is_null())
+    callback.Run(result);
+
+  return result;
 }
 
 }  // namespace
@@ -168,7 +174,10 @@ void ImportantFileWriter::WriteNow(std::unique_ptr<std::string> data) {
   if (HasPendingWrite())
     timer_.Stop();
 
-  auto task = Bind(&WriteScopedStringToFileAtomically, path_, Passed(&data));
+  auto task = Bind(&WriteScopedStringToFileAtomically, path_, Passed(&data),
+                   on_next_write_callback_);
+  on_next_write_callback_.Reset();
+
   if (!PostWriteTask(task)) {
     // Posting the task to background message loop is not expected
     // to fail, but if it does, avoid losing data and just hit the disk
@@ -203,10 +212,16 @@ void ImportantFileWriter::DoScheduledWrite() {
   serializer_ = nullptr;
 }
 
-void ImportantFileWriter::RegisterOnNextSuccessfulWriteCallback(
-    const Closure& on_next_successful_write) {
-  DCHECK(on_next_successful_write_.is_null());
-  on_next_successful_write_ = on_next_successful_write;
+void ImportantFileWriter::RegisterOnNextSuccessfulWriteReply(
+    const Closure& on_next_successful_write_reply) {
+  DCHECK(on_next_successful_write_reply_.is_null());
+  on_next_successful_write_reply_ = on_next_successful_write_reply;
+}
+
+void ImportantFileWriter::RegisterOnNextWriteSynchronousCallback(
+    const Callback<void(bool success)>& on_next_write_callback) {
+  DCHECK(on_next_write_callback_.is_null());
+  on_next_write_callback_ = on_next_write_callback;
 }
 
 bool ImportantFileWriter::PostWriteTask(const Callback<bool()>& task) {
@@ -215,7 +230,7 @@ bool ImportantFileWriter::PostWriteTask(const Callback<bool()>& task) {
   // PostTaskAndReply causes memory leaks in tests (crbug.com/371974) and
   // suppressing all of those is unrealistic hence we avoid most of them by
   // using PostTask() in the typical scenario below.
-  if (!on_next_successful_write_.is_null()) {
+  if (!on_next_successful_write_reply_.is_null()) {
     return PostTaskAndReplyWithResult(
         task_runner_.get(),
         FROM_HERE,
@@ -230,9 +245,9 @@ bool ImportantFileWriter::PostWriteTask(const Callback<bool()>& task) {
 
 void ImportantFileWriter::ForwardSuccessfulWrite(bool result) {
   DCHECK(CalledOnValidThread());
-  if (result && !on_next_successful_write_.is_null()) {
-    on_next_successful_write_.Run();
-    on_next_successful_write_.Reset();
+  if (result && !on_next_successful_write_reply_.is_null()) {
+    on_next_successful_write_reply_.Run();
+    on_next_successful_write_reply_.Reset();
   }
 }