(Re-landing of) Support RunOnce() in message loop.

Deeply nested calls to MessageLoop::Run() were made, and
a multitude of Quit() messages were handled at the most
nested level.  This left outer invocations hung, waiting for
"their" kQuitMsg to arrive (but the the nested loop had
already discarded them in its processing of pending messages
before exit :-/ ).

We now use a more controlled run of the message loop, which
does not rely on kQuitMsg.

This re-landing doesn't have the anti-hang assertion, which was 
breaking a lot of tests.

bug=1291034

r=darin,mpcomplete

M    base/message_loop.h
M    base/message_loop.cc
M    chrome/common/ipc_sync_channel.cc



git-svn-id: svn://svn.chromium.org/chrome/trunk/src@130 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 3 insertions, 4 deletions

diff --git a/chrome/common/ipc_sync_channel.cc b/chrome/common/ipc_sync_channel.cc
index bbd7a23..1dc106c 100644
--- a/chrome/common/ipc_sync_channel.cc
+++ b/chrome/common/ipc_sync_channel.cc
@@ -445,11 +445,10 @@ bool SyncChannel::Send(IPC::Message* message) {
       // shutdown the nested loop when there are no more messages.
       pump_messages_events_.push(pump_messages_event);
       bool old_state = MessageLoop::current()->NestableTasksAllowed();
-      // Insert a Quit message so that we just flush the MessageLoop without
-      // letting the MessageLoop wait for more messages.
-      MessageLoop::current()->Quit();
       MessageLoop::current()->SetNestableTasksAllowed(true);
-      MessageLoop::current()->Run();
+      // Process a message, but come right back out of the MessageLoop (don't
+      // loop, sleep, or wait for a kMsgQuit).
+      MessageLoop::current()->RunOnce();
       MessageLoop::current()->SetNestableTasksAllowed(old_state);
       pump_messages_events_.pop();
     } else {