Convert /headless to use ARC

See https://chromium.googlesource.com/chromium/src/+/main/docs/mac/arc.md
for information about this conversion.

This ended up only adding the ARC boilerplate as a marker to indicate
that these files were audited.

Bug: 1280317
Change-Id: Idce5fda8e9b7123cde3195e587e0e221cca0cf47
Include-Ci-Only-Tests: true
Validate-Test-Flakiness: skip
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4532582
Auto-Submit: Avi Drissman <avi@chromium.org>
Commit-Queue: Sami Kyöstilä <skyostil@chromium.org>
Reviewed-by: Sami Kyöstilä <skyostil@chromium.org>
Code-Coverage: Findit <findit-for-me@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#1144483}

headless/BUILD.gn

@@ -368,12 +368,17 @@ component("headless_non_renderer") {
     "public/util/user_agent.h",
   ]
 
+  if (is_apple) {
+    configs += [ "//build/config/compiler:enable_arc" ]
+  }
+
   if (is_mac) {
     sources += [
       "lib/browser/headless_browser_impl_mac.mm",
       "lib/browser/headless_browser_main_parts_mac.mm",
       "lib/browser/headless_shell_application_mac.h",
       "lib/browser/headless_shell_application_mac.mm",
+      "lib/headless_content_main_delegate_mac.mm",
     ]
   }
 
@@ -513,10 +518,6 @@ component("headless_non_renderer") {
     deps += [ "//ui/ozone" ]
   }
 
-  if (is_mac) {
-    sources += [ "lib/headless_content_main_delegate_mac.mm" ]
-  }
-
   if (headless_use_prefs) {
     deps += [
       "//components/origin_trials:browser",

headless/lib/browser/headless_browser_impl_mac.mm

@@ -15,6 +15,10 @@
 #import "ui/base/cocoa/base_view.h"
 #import "ui/gfx/mac/coordinate_conversion.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 // Overrides events and actions for NSPopUpButtonCell.
 @interface FakeNSPopUpButtonCell : NSObject
 @end
@@ -33,7 +37,7 @@ namespace headless {
 
 namespace {
 
-// Swizzles all event and acctions for NSPopUpButtonCell to avoid showing in
+// Swizzles all event and actions for NSPopUpButtonCell to avoid showing in
 // headless mode.
 class HeadlessPopUpMethods {
  public:
@@ -74,8 +78,8 @@ void HeadlessBrowserImpl::PlatformInitialize() {
 
 void HeadlessBrowserImpl::PlatformStart() {
   // Disallow headless to be throttled as a background process.
-  [[NSProcessInfo processInfo] beginActivityWithOptions:kActivityOptions
-                                                 reason:kActivityReason];
+  [NSProcessInfo.processInfo beginActivityWithOptions:kActivityOptions
+                                               reason:kActivityReason];
 }
 
 void HeadlessBrowserImpl::PlatformInitializeWebContents(
@@ -94,8 +98,7 @@ void HeadlessBrowserImpl::PlatformSetWebContentsBounds(
   content::WebContents* content_web_contents = web_contents->web_contents();
 
   NSView* web_view = content_web_contents->GetNativeView().GetNativeNSView();
-  NSRect frame = gfx::ScreenRectToNSRect(bounds);
-  [web_view setFrame:frame];
+  web_view.frame = gfx::ScreenRectToNSRect(bounds);
 
   // Render widget host view is not ready at this point, so post a task to set
   // bounds at later time.

headless/lib/browser/headless_browser_main_parts_mac.mm

@@ -9,11 +9,15 @@
 #include "headless/lib/browser/headless_shell_application_mac.h"
 #include "services/device/public/cpp/geolocation/system_geolocation_source_mac.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace headless {
 
 void HeadlessBrowserMainParts::PreCreateMainMessageLoop() {
   // Force hide dock and menu bar.
-  [NSApp setActivationPolicy:NSApplicationActivationPolicyAccessory];
+  NSApp.activationPolicy = NSApplicationActivationPolicyAccessory;
   if (!geolocation_manager_)
     geolocation_manager_ =
         device::SystemGeolocationSourceMac::CreateGeolocationManagerOnMac();

headless/lib/browser/headless_shell_application_mac.mm

@@ -9,7 +9,11 @@
 #include "content/public/browser/native_event_processor_mac.h"
 #include "content/public/browser/native_event_processor_observer_mac.h"
 
-@interface HeadlessShellCrApplication ()<NativeEventProcessor> {
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
+@interface HeadlessShellCrApplication () <NativeEventProcessor> {
   base::ObserverList<content::NativeEventProcessorObserver>::Unchecked
       _observers;
 }

headless/lib/headless_content_main_delegate_mac.mm

@@ -6,6 +6,10 @@
 
 #include "headless/lib/browser/headless_shell_application_mac.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace headless {
 
 void HeadlessContentMainDelegate::PlatformPreBrowserMain() {