When we process the tickler message in our windows message pump, we should not dispatch

all window messages specifically if we are in the context of a Windows modal loop, i.e.
a Windows API like TrackPopupMenu, etc. This is because these API's expect to handle
input messages like keyboard and mouse messages by peeking them from the queue and handling
them. Our message pump currently dispatches all windows messages while processing the tickler
message which causes the windows modal loop to not see keyboard and mouse messages at times.

Added a flag in the windows message loop which indicates if we are in the context of an
os modal loop. If yes we just peek for WM_PAINT and timer and dispatch those and get out.

Fixes bug http://code.google.com/p/chromium/issues/detail?id=59864

BUG=59864
Review URL: http://codereview.chromium.org/6676099

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@79248 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 13 insertions, 1 deletions

diff --git a/base/message_pump_win.cc b/base/message_pump_win.cc
index 778c2f5..1924081 100644
--- a/base/message_pump_win.cc
+++ b/base/message_pump_win.cc
@@ -6,6 +6,7 @@
 
 #include <math.h>
 
+#include "base/message_loop.h"
 #include "base/metrics/histogram.h"
 #include "base/win/wrapped_window_proc.h"
 
@@ -371,8 +372,19 @@ bool MessagePumpForUI::ProcessPumpReplacementMessage() {
   // possibly be posted), and finally dispatches that peeked replacement.  Note
   // that the re-post of kMsgHaveWork may be asynchronous to this thread!!
 
+  bool have_message = false;
   MSG msg;
-  bool have_message = (0 != PeekMessage(&msg, NULL, 0, 0, PM_REMOVE));
+  // We should not process all window messages if we are in the context of an
+  // OS modal loop, i.e. in the context of a windows API call like MessageBox.
+  // This is to ensure that these messages are peeked out by the OS modal loop.
+  if (MessageLoop::current()->os_modal_loop()) {
+    // We only peek out WM_PAINT and WM_TIMER here for reasons mentioned above.
+    have_message = PeekMessage(&msg, NULL, WM_PAINT, WM_PAINT, PM_REMOVE) ||
+                   PeekMessage(&msg, NULL, WM_TIMER, WM_TIMER, PM_REMOVE);
+  } else {
+    have_message = (0 != PeekMessage(&msg, NULL, 0, 0, PM_REMOVE));
+  }
+
   DCHECK(!have_message || kMsgHaveWork != msg.message ||
          msg.hwnd != message_hwnd_);