Handle message pump sources firing without delegates available

base/message_pump_mac.mm

 // Copyright (c) 2008 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/message_pump_mac.h"
 
 #import <AppKit/AppKit.h>
 #import <Foundation/Foundation.h>
 #include <float.h>
 
@@ skipping 163 matching lines @@
 
 // Called from the run loop.
 // static
 void MessagePumpCFRunLoopBase::RunWorkSource(void* info) {
   MessagePumpCFRunLoopBase* self = static_cast<MessagePumpCFRunLoopBase*>(info);
   self->RunWork();
 }
 
 // Called by MessagePumpCFRunLoopBase::RunWorkSource.
 bool MessagePumpCFRunLoopBase::RunWork() {
+  if (!delegate_) {
+    // This point can be reached with a NULL delegate_ if Run is not on the
+    // stack but foreign code is spinning the CFRunLoop.
+    return false;
+  }
+
   // If we're on the main event loop, the NSApp runloop won't clean up the
   // autorelease pool until there is a UI event, so use a local one for any
   // autoreleased objects to ensure they go away sooner.
   ScopedNSAutoreleasePool autorelease_pool;
 
   // Call DoWork once, and if something was done, arrange to come back here
   // again as long as the loop is still running.
   bool did_work = delegate_->DoWork();
   if (did_work) {
     CFRunLoopSourceSignal(work_source_);
   }
 
   return did_work;
 }
 
 // Called from the run loop.
 // static
 void MessagePumpCFRunLoopBase::RunDelayedWorkSource(void* info) {
   MessagePumpCFRunLoopBase* self = static_cast<MessagePumpCFRunLoopBase*>(info);
   self->RunDelayedWork();
 }
 
 // Called by MessagePumpCFRunLoopBase::RunDelayedWorkSource.
 bool MessagePumpCFRunLoopBase::RunDelayedWork() {
+  if (!delegate_) {
+    // This point can be reached with a NULL delegate_ if Run is not on the
+    // stack but foreign code is spinning the CFRunLoop.
+    return false;
+  }
+
   // If we're on the main event loop, the NSApp runloop won't clean up the
   // autorelease pool until there is a UI event, so use a local one for any
   // autoreleased objects to ensure they go away sooner.
   ScopedNSAutoreleasePool autorelease_pool;
 
   Time next_time;
   delegate_->DoDelayedWork(&next_time);
 
   bool more_work = !next_time.is_null();
   if (more_work) {
@@ skipping 14 matching lines @@
 
 // Called from the run loop.
 // static
 void MessagePumpCFRunLoopBase::RunIdleWorkSource(void* info) {
   MessagePumpCFRunLoopBase* self = static_cast<MessagePumpCFRunLoopBase*>(info);
   self->RunIdleWork();
 }
 
 // Called by MessagePumpCFRunLoopBase::RunIdleWorkSource.
 bool MessagePumpCFRunLoopBase::RunIdleWork() {
+  if (!delegate_) {
+    // This point can be reached with a NULL delegate_ if Run is not on the
+    // stack but foreign code is spinning the CFRunLoop.
+    return false;
+  }
+
   // If we're on the main event loop, the NSApp runloop won't clean up the
   // autorelease pool until there is a UI event, so use a local one for any
   // autoreleased objects to ensure they go away sooner.
   ScopedNSAutoreleasePool autorelease_pool;
 
   // Call DoIdleWork once, and if something was done, arrange to come back here
   // again as long as the loop is still running.
   bool did_work = delegate_->DoIdleWork();
   if (did_work) {
     CFRunLoopSourceSignal(idle_work_source_);
   }
 
   return did_work;
 }
 
 // Called from the run loop.
 // static
 void MessagePumpCFRunLoopBase::RunNestingDeferredWorkSource(void* info) {
   MessagePumpCFRunLoopBase* self = static_cast<MessagePumpCFRunLoopBase*>(info);
   self->RunNestingDeferredWork();
 }
 
 // Called by MessagePumpCFRunLoopBase::RunNestingDeferredWorkSource.
 bool MessagePumpCFRunLoopBase::RunNestingDeferredWork() {
+  if (!delegate_) {
+    // This point can be reached with a NULL delegate_ if Run is not on the
+    // stack but foreign code is spinning the CFRunLoop.  There's no sense in
+    // attempting to do any work or signalling the work sources because
+    // without a delegate, work is not possible.
+    return false;
+  }
+
   // Immediately try work in priority order.
   if (!RunWork()) {
     if (!RunDelayedWork()) {
       if (!RunIdleWork()) {
         return false;
       }
     } else {
       // There was no work, and delayed work was done.  Arrange for the loop
       // to try non-nestable idle work on a subsequent pass.
       CFRunLoopSourceSignal(idle_work_source_);
@@ skipping 195 matching lines @@
 // static
 MessagePump* MessagePumpMac::Create() {
   if ([NSThread isMainThread]) {
     return new MessagePumpNSApplication;
   }
 
   return new MessagePumpNSRunLoop;
 }
 
 }  // namespace base