Enable DanglingPointerDetector on Mac (dcheck && !official)

The DanglingPointerDetector is currently enabled by default on Linux,
and there are specific bots for other platforms.

This patches adds Mac by default.
Follow-ups:
- Cleanup the mac-rel config.
- Iterate for every other platforms

Benefits:
- No more CQ vs CI differences (See chromium:327473315)
- Increased coverage.

Cq-Include-Trybots: luci.chromium.try:mac_chromium_10.15_rel_ng,mac_chromium_11.0_rel_ng
Include-Ci-Only-Tests: true
Bug: chromium:328104161, chromium:327473315
Change-Id: I2a6ed0e8fdb11cb5b5868befc14fe3e4608e4498
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5371737
Commit-Queue: Arthur Sonzogni <arthursonzogni@chromium.org>
Reviewed-by: Bartek Nowierski <bartekn@chromium.org>
Auto-Submit: Arthur Sonzogni <arthursonzogni@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1280732}

base/allocator/partition_alloc_features.cc

@@ -42,10 +42,7 @@ const base::FeatureParam<UnretainedDanglingPtrMode>
 
 BASE_FEATURE(kPartitionAllocDanglingPtr,
              "PartitionAllocDanglingPtr",
-#if BUILDFLAG(ENABLE_DANGLING_RAW_PTR_FEATURE_FLAG) ||                         \
-    (BUILDFLAG(ENABLE_DANGLING_RAW_PTR_CHECKS) &&                              \
-     (BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_WIN)) && !defined(OFFICIAL_BUILD) && \
-     (!defined(NDEBUG) || DCHECK_IS_ON()))
+#if BUILDFLAG(ENABLE_DANGLING_RAW_PTR_FEATURE_FLAG)
              FEATURE_ENABLED_BY_DEFAULT
 #else
              FEATURE_DISABLED_BY_DEFAULT

base/allocator/partition_allocator/partition_alloc.gni

@@ -194,6 +194,8 @@ declare_args() {
   # This is meant to be used primarily on bots. It is much easier to override
   # the feature flags using a binary flag instead of updating multiple bots's
   # scripts to pass command line arguments.
+  #
+  # TODO(328104161): Remove this flag.
   enable_backup_ref_ptr_feature_flag = false
 
   # Build support for Dangling Ptr Detection (DPD) via BackupRefPtr (BRP),
@@ -207,7 +209,9 @@ declare_args() {
   # This is meant to be used primarily on bots. It is much easier to override
   # the feature flags using a binary flag instead of updating multiple bots's
   # scripts to pass command line arguments.
-  enable_dangling_raw_ptr_feature_flag = false
+  #
+  # TODO(328104161): Remove this flag.
+  enable_dangling_raw_ptr_feature_flag = enable_dangling_raw_ptr_checks_default
 
   enable_backup_ref_ptr_instance_tracer = false
 

build_overrides/partition_alloc.gni

@@ -77,7 +77,7 @@ enable_backup_ref_ptr_support_default = _is_brp_supported
 
 enable_backup_ref_ptr_slow_checks_default = false
 enable_dangling_raw_ptr_checks_default =
-    enable_backup_ref_ptr_support_default && (is_linux || is_win) &&
+    enable_backup_ref_ptr_support_default && (is_linux || is_win || is_mac) &&
     !is_official_build && (is_debug || dcheck_always_on)
 
 raw_ptr_zero_on_construct_default = true