Migrate FlutterRestorationPlugin, FlutterTextureRegistryRelay, FlutterScreenAndSceneIfLoaded to ARC (#51984)

Smart pointers support ARC as of #47612, and the unit tests were migrated in #48162.

Migrate `FlutterRestorationPlugin`, `FlutterTextureRegistryRelay`, and `UIViewController+FlutterScreenAndSceneIfLoaded` from MRC to ARC.  These files do not themselves import any MRC files, making them leaf nodes in the dependency graph of MRC files.  

Doing a few at a time to make the dependency graph manageable, and to easily revert if this causes retain cycles or other memory management issues.

Part of flutter/flutter#137801.

Author: jmagman

shell/platform/darwin/ios/BUILD.gn

@@ -61,9 +61,15 @@ source_set("flutter_framework_source_arc") {
   sources = [
     "framework/Source/FlutterMetalLayer.h",
     "framework/Source/FlutterMetalLayer.mm",
+    "framework/Source/FlutterRestorationPlugin.h",
+    "framework/Source/FlutterRestorationPlugin.mm",
     "framework/Source/FlutterTextInputDelegate.h",
     "framework/Source/FlutterTextInputPlugin.h",
     "framework/Source/FlutterTextInputPlugin.mm",
+    "framework/Source/FlutterTextureRegistryRelay.h",
+    "framework/Source/FlutterTextureRegistryRelay.mm",
+    "framework/Source/UIViewController+FlutterScreenAndSceneIfLoaded.h",
+    "framework/Source/UIViewController+FlutterScreenAndSceneIfLoaded.mm",
   ]
 
   frameworks = [
@@ -110,14 +116,10 @@ source_set("flutter_framework_source") {
     "framework/Source/FlutterPlatformViews_Internal.h",
     "framework/Source/FlutterPlatformViews_Internal.mm",
     "framework/Source/FlutterPluginAppLifeCycleDelegate.mm",
-    "framework/Source/FlutterRestorationPlugin.h",
-    "framework/Source/FlutterRestorationPlugin.mm",
     "framework/Source/FlutterSemanticsScrollView.h",
     "framework/Source/FlutterSemanticsScrollView.mm",
     "framework/Source/FlutterSpellCheckPlugin.h",
     "framework/Source/FlutterSpellCheckPlugin.mm",
-    "framework/Source/FlutterTextureRegistryRelay.h",
-    "framework/Source/FlutterTextureRegistryRelay.mm",
     "framework/Source/FlutterUIPressProxy.h",
     "framework/Source/FlutterUIPressProxy.mm",
     "framework/Source/FlutterUndoManagerDelegate.h",
@@ -131,8 +133,6 @@ source_set("flutter_framework_source") {
     "framework/Source/KeyCodeMap_Internal.h",
     "framework/Source/SemanticsObject.h",
     "framework/Source/SemanticsObject.mm",
-    "framework/Source/UIViewController+FlutterScreenAndSceneIfLoaded.h",
-    "framework/Source/UIViewController+FlutterScreenAndSceneIfLoaded.mm",
     "framework/Source/accessibility_bridge.h",
     "framework/Source/accessibility_bridge.mm",
     "framework/Source/accessibility_text_entry.h",

shell/platform/darwin/ios/framework/Source/FlutterRestorationPlugin.h

@@ -15,7 +15,7 @@
 - (instancetype)initWithChannel:(FlutterMethodChannel*)channel
              restorationEnabled:(BOOL)waitForData NS_DESIGNATED_INITIALIZER;
 
-@property(nonatomic, strong) NSData* restorationData;
+@property(nonatomic, copy) NSData* restorationData;
 - (void)markRestorationComplete;
 - (void)reset;
 @end

shell/platform/darwin/ios/framework/Source/FlutterRestorationPlugin.mm

@@ -9,7 +9,7 @@
 
 #include "flutter/fml/logging.h"
 
-FLUTTER_ASSERT_NOT_ARC
+FLUTTER_ASSERT_ARC
 
 @interface FlutterRestorationPlugin ()
 @property(nonatomic, copy) FlutterResult pendingRequest;
@@ -54,8 +54,7 @@ - (void)handleMethodCall:(FlutterMethodCall*)call result:(FlutterResult)result {
 
 - (void)setRestorationData:(NSData*)data {
   if (data != _restorationData) {
-    [_restorationData release];
-    _restorationData = [data retain];
+    _restorationData = [data copy];
   }
   _waitForData = NO;
   if (self.pendingRequest != nil) {
@@ -91,10 +90,4 @@ - (NSDictionary*)dataForFramework {
   };
 }
 
-- (void)dealloc {
-  [_restorationData release];
-  [_pendingRequest release];
-  [super dealloc];
-}
-
 @end

shell/platform/darwin/ios/framework/Source/FlutterTextureRegistryRelay.h

@@ -22,7 +22,7 @@ FLUTTER_DARWIN_EXPORT
 /**
  * A weak reference to a FlutterEngine that will be passed texture registration.
  */
-@property(nonatomic, assign) NSObject<FlutterTextureRegistry>* parent;
+@property(nonatomic, weak) NSObject<FlutterTextureRegistry>* parent;
 - (instancetype)initWithParent:(NSObject<FlutterTextureRegistry>*)parent;
 @end
 

shell/platform/darwin/ios/framework/Source/FlutterTextureRegistryRelay.mm

@@ -6,6 +6,8 @@
 
 #include "flutter/fml/logging.h"
 
+FLUTTER_ASSERT_ARC
+
 @implementation FlutterTextureRegistryRelay : NSObject
 
 #pragma mark - FlutterTextureRegistry

shell/platform/darwin/ios/framework/Source/UIViewController+FlutterScreenAndSceneIfLoaded.mm

@@ -5,6 +5,9 @@
 #import "flutter/shell/platform/darwin/ios/framework/Source/UIViewController+FlutterScreenAndSceneIfLoaded.h"
 
 #include "flutter/fml/logging.h"
+#import "flutter/shell/platform/darwin/common/framework/Headers/FlutterMacros.h"
+
+FLUTTER_ASSERT_ARC
 
 @implementation UIViewController (FlutterScreenAndSceneIfLoaded)