[Mac] Use object_destructInstance() if available.

chrome/browser/chrome_browser_application_mac.mm

Index: chrome/browser/chrome_browser_application_mac.mm
diff --git a/chrome/browser/chrome_browser_application_mac.mm b/chrome/browser/chrome_browser_application_mac.mm
index 3ee3dae68ed706525a6da87b4227d937c0644d6b..ee88fa83719ed97d0e2f21f11ac359225d526238 100644
--- a/chrome/browser/chrome_browser_application_mac.mm
+++ b/chrome/browser/chrome_browser_application_mac.mm
@@ -196,6 +196,19 @@ BOOL SwizzleNSExceptionInit() {
   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
@@ -205,10 +218,32 @@ BOOL SwizzleNSExceptionInit() {
   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.

   }
 }