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

content/child/indexed_db/indexed_db_message_filter.cc

Index: content/child/indexed_db/indexed_db_message_filter.cc
diff --git a/content/child/indexed_db/indexed_db_message_filter.cc b/content/child/indexed_db/indexed_db_message_filter.cc
index bce3817072bfb57d7bd559733048913fa62485ab..60c1bea68076a16789ed6595c280a92c1b98f95a 100644
--- a/content/child/indexed_db/indexed_db_message_filter.cc
+++ b/content/child/indexed_db/indexed_db_message_filter.cc
@@ -4,10 +4,8 @@
 
 #include "content/child/indexed_db/indexed_db_message_filter.h"
 
-#include "base/message_loop/message_loop_proxy.h"
 #include "content/child/indexed_db/indexed_db_dispatcher.h"
 #include "content/child/thread_safe_sender.h"
-#include "content/child/worker_thread_task_runner.h"
 #include "content/common/indexed_db/indexed_db_constants.h"
 #include "content/common/indexed_db/indexed_db_messages.h"
 
@@ -15,29 +13,26 @@ namespace content {
 
 IndexedDBMessageFilter::IndexedDBMessageFilter(
     ThreadSafeSender* thread_safe_sender)
-    : main_thread_loop_(base::MessageLoopProxy::current()),
-      thread_safe_sender_(thread_safe_sender) {}
+    : WorkerThreadMessageFilter(thread_safe_sender) {
+}
 
 IndexedDBMessageFilter::~IndexedDBMessageFilter() {}
 
-base::TaskRunner* IndexedDBMessageFilter::OverrideTaskRunnerForMessage(
-    const IPC::Message& msg) {
-  if (IPC_MESSAGE_CLASS(msg) != IndexedDBMsgStart)
-    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_.get();
-  return new WorkerThreadTaskRunner(ipc_thread_id);
+bool IndexedDBMessageFilter::ShouldHandleMessage(
+    const IPC::Message& msg) const {
+  return IPC_MESSAGE_CLASS(msg) == IndexedDBMsgStart;
 }
 
-bool IndexedDBMessageFilter::OnMessageReceived(const IPC::Message& msg) {
-  if (IPC_MESSAGE_CLASS(msg) != IndexedDBMsgStart)
-    return false;
-  IndexedDBDispatcher::ThreadSpecificInstance(thread_safe_sender_.get())
+void IndexedDBMessageFilter::OnFilteredMessageReceived(
+    const IPC::Message& msg) {
+  IndexedDBDispatcher::ThreadSpecificInstance(thread_safe_sender())
       ->OnMessageReceived(msg);
-  return true;
+}
+
+bool IndexedDBMessageFilter::GetWorkerThreadIdForMessage(
+    const IPC::Message& msg,
+    int* ipc_thread_id) {
+  return PickleIterator(msg).ReadInt(ipc_thread_id);
 }
 
 void IndexedDBMessageFilter::OnStaleMessageReceived(const IPC::Message& msg) {
@@ -57,13 +52,13 @@ void IndexedDBMessageFilter::OnStaleSuccessIDBDatabase(
     const IndexedDBDatabaseMetadata& idb_metadata) {
   if (ipc_database_id == kNoDatabase)
     return;
-  thread_safe_sender_->Send(
+  thread_safe_sender()->Send(
       new IndexedDBHostMsg_DatabaseClose(ipc_database_id));
 }
 
 void IndexedDBMessageFilter::OnStaleUpgradeNeeded(
     const IndexedDBMsg_CallbacksUpgradeNeeded_Params& p) {
-  thread_safe_sender_->Send(
+  thread_safe_sender()->Send(
       new IndexedDBHostMsg_DatabaseClose(p.ipc_database_id));
 }