Make JSONParser a pure interface.

components/safe_json/safe_json_parser_impl.cc

Index: components/safe_json/safe_json_parser_impl.cc
diff --git a/components/safe_json/safe_json_parser.cc b/components/safe_json/safe_json_parser_impl.cc
similarity index 63%
copy from components/safe_json/safe_json_parser.cc
copy to components/safe_json/safe_json_parser_impl.cc
index af30a19f2d7be77f18052233b91acff618c1e833..0b4823e43b883d686650e034e7c2e90d77a37c22 100644
--- a/components/safe_json/safe_json_parser.cc
+++ b/components/safe_json/safe_json_parser_impl.cc
@@ -2,11 +2,9 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "components/safe_json/safe_json_parser.h"
+#include "components/safe_json/safe_json_parser_impl.h"
 
-#include <string>
-
-#include "base/single_thread_task_runner.h"
+#include "base/sequenced_task_runner.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/thread_task_runner_handle.h"
 #include "base/tuple.h"
@@ -23,26 +21,17 @@ using content::UtilityProcessHost;
 
 namespace safe_json {
 
-SafeJsonParser::SafeJsonParser(const std::string& unsafe_json,
-                               const SuccessCallback& success_callback,
-                               const ErrorCallback& error_callback)
+SafeJsonParserImpl::SafeJsonParserImpl(const std::string& unsafe_json,
+                                       const SuccessCallback& success_callback,
+                                       const ErrorCallback& error_callback)
     : unsafe_json_(unsafe_json),
       success_callback_(success_callback),
-      error_callback_(error_callback) {
-}
-
-void SafeJsonParser::Start() {
-  caller_task_runner_ = base::ThreadTaskRunnerHandle::Get();
-
-  BrowserThread::PostTask(
-      BrowserThread::IO, FROM_HERE,
-      base::Bind(&SafeJsonParser::StartWorkOnIOThread, this));
-}
+      error_callback_(error_callback) {}
 
-SafeJsonParser::~SafeJsonParser() {
+SafeJsonParserImpl::~SafeJsonParserImpl() {
 }
 
-void SafeJsonParser::StartWorkOnIOThread() {
+void SafeJsonParserImpl::StartWorkOnIOThread() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
   UtilityProcessHost* host = UtilityProcessHost::Create(
       this, base::ThreadTaskRunnerHandle::Get().get());
@@ -51,7 +40,7 @@ void SafeJsonParser::StartWorkOnIOThread() {
   host->Send(new SafeJsonParserMsg_ParseJSON(unsafe_json_));
 }
 
-void SafeJsonParser::OnJSONParseSucceeded(const base::ListValue& wrapper) {
+void SafeJsonParserImpl::OnJSONParseSucceeded(const base::ListValue& wrapper) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
   const base::Value* value = NULL;
   CHECK(wrapper.Get(0, &value));
@@ -60,26 +49,22 @@ void SafeJsonParser::OnJSONParseSucceeded(const base::ListValue& wrapper) {
   ReportResults();
 }
 
-void SafeJsonParser::OnJSONParseFailed(const std::string& error_message) {
+void SafeJsonParserImpl::OnJSONParseFailed(const std::string& error_message) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
   error_ = error_message;
   ReportResults();
 }
 
-void SafeJsonParser::ReportResults() {
+void SafeJsonParserImpl::ReportResults() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
 
   caller_task_runner_->PostTask(
       FROM_HERE,
-      base::Bind(&SafeJsonParser::ReportResultsOnOriginThread, this));
+      base::Bind(&SafeJsonParserImpl::ReportResultsOnOriginThread, this));
 }
 
-void SafeJsonParser::ReportResultsOnOriginThread() {
-  // Current callers of this class are known to either come from
-  // the UI or IO threads. This DCHECK can be removed/further enhanced
-  // in case this class is useable outside of these contexts.
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI) ||
-         BrowserThread::CurrentlyOn(BrowserThread::IO));
+void SafeJsonParserImpl::ReportResultsOnOriginThread() {
+  DCHECK(caller_task_runner_->RunsTasksOnCurrentThread());
   if (error_.empty() && parsed_json_) {
     if (!success_callback_.is_null())
       success_callback_.Run(parsed_json_.Pass());
@@ -89,9 +74,9 @@ void SafeJsonParser::ReportResultsOnOriginThread() {
   }
 }
 
-bool SafeJsonParser::OnMessageReceived(const IPC::Message& message) {
+bool SafeJsonParserImpl::OnMessageReceived(const IPC::Message& message) {
   bool handled = true;
-  IPC_BEGIN_MESSAGE_MAP(SafeJsonParser, message)
+  IPC_BEGIN_MESSAGE_MAP(SafeJsonParserImpl, message)
     IPC_MESSAGE_HANDLER(SafeJsonParserHostMsg_ParseJSON_Succeeded,
                         OnJSONParseSucceeded)
     IPC_MESSAGE_HANDLER(SafeJsonParserHostMsg_ParseJSON_Failed,
@@ -101,4 +86,12 @@ bool SafeJsonParser::OnMessageReceived(const IPC::Message& message) {
   return handled;
 }
 
+void SafeJsonParserImpl::Start() {
+  caller_task_runner_ = base::ThreadTaskRunnerHandle::Get();
+
+  BrowserThread::PostTask(
+      BrowserThread::IO, FROM_HERE,
+      base::Bind(&SafeJsonParserImpl::StartWorkOnIOThread, this));
+}
+
 }  // namespace safe_json