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

content/child/quota_message_filter.cc

Index: content/child/quota_message_filter.cc
diff --git a/content/child/quota_message_filter.cc b/content/child/quota_message_filter.cc
index 139be2550deff675625eda80fa407dc53258c962..e9290e489d9a1127e1a8c9e90df290b3f8680a77 100644
--- a/content/child/quota_message_filter.cc
+++ b/content/child/quota_message_filter.cc
@@ -4,19 +4,13 @@
 
 #include "content/child/quota_message_filter.h"
 
-#include "base/message_loop/message_loop_proxy.h"
 #include "content/child/quota_dispatcher.h"
-#include "content/child/thread_safe_sender.h"
-#include "content/child/worker_thread_task_runner.h"
 #include "content/common/quota_messages.h"
 
 namespace content {
 
-QuotaMessageFilter::QuotaMessageFilter(
-    ThreadSafeSender* thread_safe_sender)
-    : main_thread_loop_proxy_(base::MessageLoopProxy::current()),
-      thread_safe_sender_(thread_safe_sender),
-      next_request_id_(0) {
+QuotaMessageFilter::QuotaMessageFilter(ThreadSafeSender* thread_safe_sender)
+    : WorkerThreadMessageFilter(thread_safe_sender), next_request_id_(0) {
 }
 
 QuotaMessageFilter::~QuotaMessageFilter() {}
@@ -38,35 +32,29 @@ void QuotaMessageFilter::ClearThreadRequests(int thread_id) {
   }
 }
 
-base::TaskRunner* QuotaMessageFilter::OverrideTaskRunnerForMessage(
-    const IPC::Message& msg) {
-  if (IPC_MESSAGE_CLASS(msg) != QuotaMsgStart)
-    return NULL;
+bool QuotaMessageFilter::ShouldHandleMessage(const IPC::Message& msg) const {
+  return IPC_MESSAGE_CLASS(msg) == QuotaMsgStart;
+}
 
-  int request_id = -1, thread_id = 0;
+void QuotaMessageFilter::OnFilteredMessageReceived(const IPC::Message& msg) {
+  QuotaDispatcher::ThreadSpecificInstance(thread_safe_sender(), this)
+      ->OnMessageReceived(msg);
+}
+
+bool QuotaMessageFilter::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_);
-    RequestIdToThreadId::iterator found = request_id_map_.find(request_id);
-    if (found != request_id_map_.end()) {
-      thread_id = found->second;
-      request_id_map_.erase(found);
-    }
+  base::AutoLock lock(request_id_map_lock_);
+  RequestIdToThreadId::iterator found = request_id_map_.find(request_id);
+  if (found != request_id_map_.end()) {
+    *ipc_thread_id = found->second;
+    request_id_map_.erase(found);
+    return true;
   }
-
-  if (!thread_id)
-    return main_thread_loop_proxy_.get();
-  return new WorkerThreadTaskRunner(thread_id);
-}
-
-bool QuotaMessageFilter::OnMessageReceived(const IPC::Message& msg) {
-  if (IPC_MESSAGE_CLASS(msg) != QuotaMsgStart)
-    return false;
-  QuotaDispatcher::ThreadSpecificInstance(thread_safe_sender_.get(), this)
-      ->OnMessageReceived(msg);
-  return true;
+  return false;
 }
 
 }  // namespace content