[Mac] Ignore spell-checker exceptions.

base/mac/scoped_nsexception_enabler.mm

 // Copyright (c) 2011 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.
 
 #import "base/mac/scoped_nsexception_enabler.h"
 
 #import "base/lazy_instance.h"
 #import "base/threading/thread_local.h"
 
 // To make the |g_exceptionsAllowed| declaration readable.
 using base::LazyInstance;
 using base::LeakyLazyInstanceTraits;
 using base::ThreadLocalBoolean;
 
+// When C++ exceptions are disabled, the C++ library defines |try| and
+// |catch| so as to allow exception-expecting C++ code to build properly when
+// language support for exceptions is not present.  These macros interfere
+// with the use of |@try| and |@catch| in Objective-C files such as this one.
+// Undefine these macros here, after everything has been #included, since
+// there will be no C++ uses and only Objective-C uses from this point on.
+#undef try
+#undef catch
+
 namespace {
 
 // Whether to allow NSExceptions to be raised on the current thread.
 LazyInstance<ThreadLocalBoolean, LeakyLazyInstanceTraits<ThreadLocalBoolean> >
     g_exceptionsAllowed = LAZY_INSTANCE_INITIALIZER;
 
 }  // namespace
 
 namespace base {
 namespace mac {
 
 bool GetNSExceptionsAllowed() {
   return g_exceptionsAllowed.Get().Get();
 }
 
 void SetNSExceptionsAllowed(bool allowed) {
   return g_exceptionsAllowed.Get().Set(allowed);
 }
 
+id PerformSelectorIgnoringExceptions(NSObject* target, SEL sel) {
+  id ret = nil;
+  @try {
+    base::mac::ScopedNSExceptionEnabler enable;
+    ret = [target performSelector:sel];
+  }
+  @catch(id exception) {
+  }
+  return ret;
+}
+
 ScopedNSExceptionEnabler::ScopedNSExceptionEnabler() {
   was_enabled_ = GetNSExceptionsAllowed();
   SetNSExceptionsAllowed(true);
 }
 
 ScopedNSExceptionEnabler::~ScopedNSExceptionEnabler() {
   SetNSExceptionsAllowed(was_enabled_);
 }
 
 }  // namespace mac
 }  // namespace base