[Mac] Use object_destructInstance() if available.

chrome/browser/chrome_browser_application_mac.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 "chrome/browser/chrome_browser_application_mac.h"
 
 #import "base/logging.h"
 #import "base/mac/scoped_nsexception_enabler.h"
 #import "base/metrics/histogram.h"
 #import "base/memory/scoped_nsobject.h"
@@ skipping 178 matching lines @@
 // -[NSException raise] when DCHECK() is turned on (as opposed to
 // replicating the preprocess logic which turns DCHECK() on).
 BOOL SwizzleNSExceptionInit() {
   gOriginalInitIMP = ObjcEvilDoers::SwizzleImplementedInstanceMethods(
       [NSException class],
       @selector(initWithName:reason:userInfo:),
       @selector(chromeInitWithName:reason:userInfo:));
   return YES;
 }
 
+// Failures for purposes of monitoring success setting up zombies.
+enum ZombieFailure {
+  FAILED_10_5,
+  FAILED_10_6,
+
+  // Add new versions before here.
+  FAILED_MAX,
+};
+
+void RecordZombieFailure(ZombieFailure failure) {
+  UMA_HISTOGRAM_ENUMERATION("OSX.ZombieEnableFailure", failure, FAILED_MAX);

[Mark Mentovai, 2011/06/07 21:42:57]

I don’t remember if you need to edit some file to get these recognized properly.

[Scott Hess - ex-Googler, 2011/06/07 23:48:21]

They're reported as hashes, so you need to tell another tool about the hashes. 
I'll follow up with jar on that.

+}
+
 }  // namespace
 
 @implementation BrowserCrApplication
 
 + (void)initialize {
   // Whitelist releases that are compatible with objc zombies.
   int32 major_version = 0, minor_version = 0, bugfix_version = 0;
   base::SysInfo::OperatingSystemVersionNumbers(
       &major_version, &minor_version, &bugfix_version);
-  if (major_version == 10 && (minor_version == 5 || minor_version == 6)) {
-    // Turn all deallocated Objective-C objects into zombies, keeping
-    // the most recent 10,000 of them on the treadmill.
-    ObjcEvilDoers::ZombieEnable(YES, 10000);
+
+  // Turn all deallocated Objective-C objects into zombies, keeping
+  // the most recent 10,000 of them on the treadmill.
+  static const size_t kTreadmillSize = 10000;
+  if (major_version == 10) {
+    if (minor_version == 5) {
+      if (!ObjcEvilDoers::ZombieEnable(ObjcEvilDoers::RUNTIME_10_5, YES,
+                                       kTreadmillSize)) {
+        RecordZombieFailure(FAILED_10_5);
+      }
+    } else if (minor_version == 6) {
+      if (!ObjcEvilDoers::ZombieEnable(ObjcEvilDoers::RUNTIME_10_6, YES,
+                                       kTreadmillSize)) {
+        RecordZombieFailure(FAILED_10_6);
+      }
+    } else if (minor_version > 6) {
+      // Assume the future looks like the present.
+      if (!ObjcEvilDoers::ZombieEnable(ObjcEvilDoers::RUNTIME_10_6, YES,
+                                       kTreadmillSize)) {
+        // Put all future failures into the MAX bin.  New OS releases
+        // come out infrequently enough that this should always
+        // correspond to "Next release", and once the next release
+        // happens that bin will get an official name.
+        RecordZombieFailure(FAILED_MAX);
+      }
+    }

[Scott Hess - ex-Googler, 2011/06/07 21:24:51]

I am not really happy with this code.  But it wasn't tons better written other
ways.  At least this way it reads top-to-bottom ...

[Mark Mentovai, 2011/06/07 21:42:57]

shess wrote:
Just a suggestion as to an alternative: you could have two variables, one for
ObjcEvilDoers::RUNTIME_* and the other for FAILED_*, set them up properly, and
then just have |if (!ZombieEnable(r)) RecordFailure(f);| once.

   }
 }
 
 - init {
   CHECK(SwizzleNSExceptionInit());
   return [super init];
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // HISTORICAL COMMENT (by viettrungluu, from
@@ skipping 206 matching lines @@
         if (RenderViewHost* rvh = contents->render_view_host()) {
           rvh->EnableRendererAccessibility();
         }
       }
     }
   }
   return [super accessibilitySetValue:value forAttribute:attribute];
 }
 
 @end