workers: Introduce a WorkerMessageFilter to ease routing/processing worker messages.

content/child/geofencing/geofencing_message_filter.cc

Index: content/child/geofencing/geofencing_message_filter.cc
diff --git a/content/child/geofencing/geofencing_message_filter.cc b/content/child/geofencing/geofencing_message_filter.cc
index a8334571d5b4f20eb6ca13f3724c760680ddd31b..a866b378f395bf35992b4b2bd8b9903a63468f2e 100644
--- a/content/child/geofencing/geofencing_message_filter.cc
+++ b/content/child/geofencing/geofencing_message_filter.cc
@@ -4,40 +4,33 @@
 
 #include "content/child/geofencing/geofencing_message_filter.h"
 
-#include "base/message_loop/message_loop_proxy.h"
 #include "content/child/geofencing/geofencing_dispatcher.h"
-#include "content/child/thread_safe_sender.h"
-#include "content/child/worker_thread_task_runner.h"
 #include "ipc/ipc_message_macros.h"
 
 namespace content {
 
 GeofencingMessageFilter::GeofencingMessageFilter(ThreadSafeSender* sender)
-    : main_thread_loop_proxy_(base::MessageLoopProxy::current()),
-      thread_safe_sender_(sender) {
+    : WorkerThreadMessageFilter(sender) {
 }
 
 GeofencingMessageFilter::~GeofencingMessageFilter() {
 }
 
-base::TaskRunner* GeofencingMessageFilter::OverrideTaskRunnerForMessage(
+bool GeofencingMessageFilter::ShouldHandleMessage(
+    const IPC::Message& msg) const {
+  return IPC_MESSAGE_CLASS(msg) == GeofencingMsgStart;
+}
+
+void GeofencingMessageFilter::OnFilteredMessageReceived(
     const IPC::Message& msg) {
-  if (IPC_MESSAGE_CLASS(msg) != GeofencingMsgStart)
-    return NULL;
-  int ipc_thread_id = 0;
-  const bool success = PickleIterator(msg).ReadInt(&ipc_thread_id);
-  DCHECK(success);
-  if (!ipc_thread_id)
-    return main_thread_loop_proxy_.get();
-  return new WorkerThreadTaskRunner(ipc_thread_id);
+  GeofencingDispatcher::GetOrCreateThreadSpecificInstance(thread_safe_sender())
+      ->OnMessageReceived(msg);
 }
 
-bool GeofencingMessageFilter::OnMessageReceived(const IPC::Message& msg) {
-  if (IPC_MESSAGE_CLASS(msg) != GeofencingMsgStart)
-    return false;
-  GeofencingDispatcher::GetOrCreateThreadSpecificInstance(
-      thread_safe_sender_.get())->OnMessageReceived(msg);
-  return true;
+bool GeofencingMessageFilter::GetWorkerThreadIdForMessage(
+    const IPC::Message& msg,
+    int* ipc_thread_id) {
+  return PickleIterator(msg).ReadInt(ipc_thread_id);
 }
 
 }  // namespace content