[ObjC ARC] Converts ios/chrome/browser/ui/stack_view:stack_view to ARC.

ios/chrome/browser/metrics/BUILD.gn

Index: ios/chrome/browser/metrics/BUILD.gn
diff --git a/ios/chrome/browser/metrics/BUILD.gn b/ios/chrome/browser/metrics/BUILD.gn
index feff38a2a832e71638da3a5b9ac1949591d6f74b..5b55c011325bac3232dc8d97614e5b4aca8bd596 100644
--- a/ios/chrome/browser/metrics/BUILD.gn
+++ b/ios/chrome/browser/metrics/BUILD.gn
@@ -93,8 +93,6 @@ source_set("metrics_internal") {
     "size_class_recorder.h",
     "size_class_recorder.mm",
     "size_class_recorder_private.h",
-    "tab_usage_recorder.h",
-    "tab_usage_recorder.mm",
     "tab_usage_recorder_delegate.h",
   ]
   deps = [
@@ -111,17 +109,41 @@ source_set("metrics_internal") {
   ]
   public_deps = [
     ":metrics_internal_arc",
+    ":metrics_internal_noarc",
+  ]
+  allow_circular_includes_from = [
+    ":metrics_internal_arc",
+    ":metrics_internal_noarc",
   ]
-  allow_circular_includes_from = [ ":metrics_internal_arc" ]
   libs = [ "UIKit.framework" ]
 }
 
+source_set("metrics_internal_noarc") {
+  # TODO(crbug.com/731724) This target shouldn't be compiled with ARC until
+  # after it's converted to use WebStates instead of Tabs.
+  cflags_objc = [ "-fno-objc-arc" ]
+
+  sources = [
+    "tab_usage_recorder.h",
+    "tab_usage_recorder.mm",
+  ]
+
+  deps = [
+    ":metrics",
+    "//base",
+    "//ios/chrome/browser",
+    "//ios/chrome/browser/tabs",
+    "//ios/web",
+  ]
+}
+
 source_set("metrics_internal_arc") {
   sources = [
     "tab_usage_recorder_web_state_list_observer.h",
     "tab_usage_recorder_web_state_list_observer.mm",
   ]
   deps = [
+    ":metrics_internal_noarc",
     "//base",
     "//ios/chrome/browser/tabs",
     "//ios/chrome/browser/web_state_list",