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

ios/chrome/app/main_controller.h

Index: ios/chrome/app/main_controller.h
diff --git a/ios/chrome/app/main_controller.h b/ios/chrome/app/main_controller.h
index 9181a6ce74bc223f98ddc760abc12eaeebc6c375..22d9fd79243f4d27b3de67f380eda535a11f6ce6 100644
--- a/ios/chrome/app/main_controller.h
+++ b/ios/chrome/app/main_controller.h
@@ -30,19 +30,19 @@
                                      TabSwitching>
 
 // A BrowserViewInformation object to perform BrowserViewController operations.
-@property(nonatomic, readonly) id<BrowserViewInformation>
+@property(weak, nonatomic, readonly) id<BrowserViewInformation>
     browserViewInformation;
 
 // The application window.
-@property(nonatomic, retain) UIWindow* window;
+@property(nonatomic, strong) UIWindow* window;
 
 // Contains information about the application state, for example whether the
 // safe mode is activated.
-@property(nonatomic, assign) AppState* appState;
+@property(nonatomic, weak) AppState* appState;
 
 // This metrics mediator is used to check and update the metrics accordingly to
 // to the user preferences.
-@property(nonatomic, assign) MetricsMediator* metricsMediator;
+@property(nonatomic, weak) MetricsMediator* metricsMediator;
 
 // UIResponder addition to execute a Chrome command.  Overridden in UIWindow to
 // forward the call to the application delegate. The application delegate