Make SyncMessageFilter work with WebKit threads.

SyncMessageFilter doesn't work with WebKit threads, because WebKit
threads don't have MessageLoops, so two threads send a message at the
same time, the first thread will stay blocked forever.

Also, it's unclear why we need to use MessageLoops as keys in a
hash_maps. The code doesn't use them at all.

TEST=a DB example that used to deadlock is working now
BUG=45253

Review URL: http://codereview.chromium.org/2360003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@48556 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 9 insertions, 22 deletions

diff --git a/ipc/ipc_sync_message_filter.cc b/ipc/ipc_sync_message_filter.cc
index db3f86e..6a719f9 100644
--- a/ipc/ipc_sync_message_filter.cc
+++ b/ipc/ipc_sync_message_filter.cc
@@ -48,7 +48,7 @@ bool SyncMessageFilter::Send(Message* message) {
     // Also by definition, can't use this on IO thread since we're blocking it.
     DCHECK(MessageLoop::current() != listener_loop_);
     DCHECK(MessageLoop::current() != io_loop_);
-    pending_sync_messages_[MessageLoop::current()] = &pending_message;
+    pending_sync_messages_.insert(&pending_message);
   }
 
   io_loop_->PostTask(
@@ -61,7 +61,7 @@ bool SyncMessageFilter::Send(Message* message) {
   {
     AutoLock auto_lock(lock_);
     delete pending_message.deserializer;
-    pending_sync_messages_.erase(MessageLoop::current());
+    pending_sync_messages_.erase(&pending_message);
   }
 
   return pending_message.send_result;
@@ -86,7 +86,7 @@ void SyncMessageFilter::SignalAllEvents() {
   AutoLock auto_lock(lock_);
   for (PendingSyncMessages::iterator iter = pending_sync_messages_.begin();
        iter != pending_sync_messages_.end(); ++iter) {
-    iter->second->done_event->Signal();
+    (*iter)->done_event->Signal();
   }
 }
 
@@ -110,12 +110,12 @@ bool SyncMessageFilter::OnMessageReceived(const Message& message) {
   AutoLock auto_lock(lock_);
   for (PendingSyncMessages::iterator iter = pending_sync_messages_.begin();
        iter != pending_sync_messages_.end(); ++iter) {
-    if (SyncMessage::IsMessageReplyTo(message, iter->second->id)) {
+    if (SyncMessage::IsMessageReplyTo(message, (*iter)->id)) {
       if (!message.is_reply_error()) {
-        iter->second->send_result =
-            iter->second->deserializer->SerializeOutputParameters(message);
+        (*iter)->send_result =
+            (*iter)->deserializer->SerializeOutputParameters(message);
       }
-      iter->second->done_event->Signal();
+      (*iter)->done_event->Signal();
       return true;
     }
   }
diff --git a/ipc/ipc_sync_message_filter.h b/ipc/ipc_sync_message_filter.h
index 71d24c1..87fd612 100644
--- a/ipc/ipc_sync_message_filter.h
+++ b/ipc/ipc_sync_message_filter.h
@@ -6,28 +6,15 @@
 #define IPC_IPC_SYNC_MESSAGE_FILTER_H_
 
 #include "base/basictypes.h"
-#include "base/hash_tables.h"
 #include "base/lock.h"
 #include "base/ref_counted.h"
 #include "base/waitable_event.h"
 #include "ipc/ipc_channel_proxy.h"
 #include "ipc/ipc_sync_message.h"
+#include <set>
 
 class MessageLoop;
 
-#if defined(COMPILER_GCC)
-// Allows us to use MessageLoop in a hash_map with gcc (MSVC is okay without
-// specifying this).
-namespace __gnu_cxx {
-template<>
-struct hash<MessageLoop*> {
-  size_t operator()(MessageLoop* message_loop) const {
-    return reinterpret_cast<size_t>(message_loop);
-  }
-};
-}
-#endif
-
 namespace IPC {
 
 class MessageReplyDeserializer;
@@ -63,7 +50,7 @@ class SyncMessageFilter : public ChannelProxy::MessageFilter,
   MessageLoop* listener_loop_;  // The process's main thread.
   MessageLoop* io_loop_;  // The message loop where the Channel lives.
 
-  typedef base::hash_map<MessageLoop*, PendingSyncMsg*> PendingSyncMessages;
+  typedef std::set<PendingSyncMsg*> PendingSyncMessages;
   PendingSyncMessages pending_sync_messages_;
 
   // Locks data members above.