[ObjC ARC] Converts ios/chrome/app:app to ARC.

ios/chrome/app/safe_mode_crashing_modules_config.mm

Index: ios/chrome/app/safe_mode_crashing_modules_config.mm
diff --git a/ios/chrome/app/safe_mode_crashing_modules_config.mm b/ios/chrome/app/safe_mode_crashing_modules_config.mm
index e9ec67c4f1d437a1c26fc6be20a8bf5ff6a5cfeb..2cde7adf9bfb714eda16c32447fe76337b34576c 100644
--- a/ios/chrome/app/safe_mode_crashing_modules_config.mm
+++ b/ios/chrome/app/safe_mode_crashing_modules_config.mm
@@ -6,7 +6,10 @@
 
 #include "base/logging.h"
 #include "base/mac/foundation_util.h"
-#import "base/mac/scoped_nsobject.h"
+
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
 
 namespace {
 
@@ -15,12 +18,9 @@ NSString* const kModuleFriendlyNameKey = @"ModuleFriendlyName";
 
 }  // namespace
 
-@interface SafeModeCrashingModulesConfig () {
-  base::scoped_nsobject<NSDictionary> _configuration;
+@implementation SafeModeCrashingModulesConfig {
+  NSDictionary* _configuration;
 }
-@end
-
-@implementation SafeModeCrashingModulesConfig
 
 + (SafeModeCrashingModulesConfig*)sharedInstance {
   static SafeModeCrashingModulesConfig* instance =
@@ -34,8 +34,7 @@ NSString* const kModuleFriendlyNameKey = @"ModuleFriendlyName";
     NSString* configPath =
         [[NSBundle mainBundle] pathForResource:@"SafeModeCrashingModules"
                                         ofType:@"plist"];
-    _configuration.reset(
-        [[NSDictionary alloc] initWithContentsOfFile:configPath]);
+    _configuration = [[NSDictionary alloc] initWithContentsOfFile:configPath];
   }
   return self;
 }