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

content/child/push_messaging/push_dispatcher.cc

Index: content/child/push_messaging/push_dispatcher.cc
diff --git a/content/child/push_messaging/push_dispatcher.cc b/content/child/push_messaging/push_dispatcher.cc
index 4bd1705adbe1fe7104e0bc8dc9cc94b0aadd5e1d..8cc33fc0dd20e53164d0fa60fbb94cd763af0b36 100644
--- a/content/child/push_messaging/push_dispatcher.cc
+++ b/content/child/push_messaging/push_dispatcher.cc
@@ -4,19 +4,13 @@
 
 #include "content/child/push_messaging/push_dispatcher.h"
 
-#include "base/message_loop/message_loop_proxy.h"
-#include "base/pickle.h"
 #include "content/child/push_messaging/push_provider.h"
-#include "content/child/thread_safe_sender.h"
-#include "content/child/worker_thread_task_runner.h"
 #include "content/common/push_messaging_messages.h"
 
 namespace content {
 
 PushDispatcher::PushDispatcher(ThreadSafeSender* thread_safe_sender)
-    : main_thread_loop_proxy_(base::MessageLoopProxy::current()),
-      thread_safe_sender_(thread_safe_sender),
-      next_request_id_(0) {
+    : WorkerThreadMessageFilter(thread_safe_sender), next_request_id_(0) {
 }
 
 PushDispatcher::~PushDispatcher() {
@@ -28,43 +22,7 @@ int PushDispatcher::GenerateRequestId(int thread_id) {
   return next_request_id_++;
 }
 
-base::TaskRunner* PushDispatcher::OverrideTaskRunnerForMessage(
-    const IPC::Message& msg) {
-  if (!ShouldHandleMessage(msg))
-    return nullptr;
-
-  int request_id = -1;
-  int thread_id = 0;
-
-  const bool success = PickleIterator(msg).ReadInt(&request_id);
-  DCHECK(success);
-
-  {
-    base::AutoLock lock(request_id_map_lock_);
-    auto it = request_id_map_.find(request_id);
-    if (it != request_id_map_.end()) {
-      thread_id = it->second;
-      request_id_map_.erase(it);
-    }
-  }
-
-  if (!thread_id)
-    return main_thread_loop_proxy_.get();
-
-  return new WorkerThreadTaskRunner(thread_id);
-}
-
-bool PushDispatcher::OnMessageReceived(const IPC::Message& msg) {
-  if (!ShouldHandleMessage(msg))
-    return false;
-
-  bool handled = PushProvider::ThreadSpecificInstance(
-                     thread_safe_sender_.get(), this)->OnMessageReceived(msg);
-  DCHECK(handled);
-  return handled;
-}
-
-bool PushDispatcher::ShouldHandleMessage(const IPC::Message& msg) {
+bool PushDispatcher::ShouldHandleMessage(const IPC::Message& msg) const {
   // Note that not all Push API IPC messages flow through this class. A subset
   // of the API functionality requires a direct association with a document and
   // a frame, and for those cases the IPC messages are handled by a
@@ -79,4 +37,27 @@ bool PushDispatcher::ShouldHandleMessage(const IPC::Message& msg) {
          msg.type() == PushMessagingMsg_UnregisterError::ID;
 }
 
+void PushDispatcher::OnFilteredMessageReceived(const IPC::Message& msg) {
+  bool handled = PushProvider::ThreadSpecificInstance(
+                     thread_safe_sender(), this)->OnMessageReceived(msg);
+  DCHECK(handled);
+}
+
+bool PushDispatcher::GetWorkerThreadIdForMessage(const IPC::Message& msg,
+                                                 int* ipc_thread_id) {
+  int request_id = -1;
+
+  const bool success = PickleIterator(msg).ReadInt(&request_id);
+  DCHECK(success);
+
+  base::AutoLock lock(request_id_map_lock_);
+  auto it = request_id_map_.find(request_id);
+  if (it != request_id_map_.end()) {
+    *ipc_thread_id = it->second;
+    request_id_map_.erase(it);
+    return true;
+  }
+  return false;
+}
+
 }  // namespace content