macOS: Fix crash when showing a select popup with CefDoMessageLoopWork (issue #2495)

Author: magreenblatt

patch/patch.cfg

@@ -390,5 +390,10 @@ patches = [
     # Fix redraw of OSR PDF viewer.
     # https://bitbucket.org/chromiumembedded/cef/issues/2507
     'name': 'browser_child_frame_2507',
+  },
+  {
+    # macOS: Fix crash when showing a select popup with CefDoMessageLoopWork.
+    # https://bitbucket.org/chromiumembedded/cef/issues/2495
+    'name': 'message_pump_mac_2495',
   }
 ]

patch/patches/message_pump_mac_2495.patch

@@ -0,0 +1,24 @@
+diff --git base/message_loop/message_pump_mac.mm base/message_loop/message_pump_mac.mm
+index fb2520179995..165a8d4b4b29 100644
+--- base/message_loop/message_pump_mac.mm
++++ base/message_loop/message_pump_mac.mm
+@@ -761,7 +761,8 @@ explicit MessagePumpScopedAutoreleasePool(MessagePumpCFRunLoopBase* pump) :
+ #else
+ 
+ ScopedPumpMessagesInPrivateModes::ScopedPumpMessagesInPrivateModes() {
+-  DCHECK(g_app_pump);
++  if (!g_app_pump)
++    return;
+   DCHECK_EQ(kNSApplicationModalSafeModeMask, g_app_pump->GetModeMask());
+   // Pumping events in private runloop modes is known to interact badly with
+   // app modal windows like NSAlert.
+@@ -770,7 +771,8 @@ explicit MessagePumpScopedAutoreleasePool(MessagePumpCFRunLoopBase* pump) :
+ }
+ 
+ ScopedPumpMessagesInPrivateModes::~ScopedPumpMessagesInPrivateModes() {
+-  DCHECK(g_app_pump);
++  if (!g_app_pump)
++    return;
+   g_app_pump->SetModeMask(kNSApplicationModalSafeModeMask);
+ }
+