Add feature flag for landscape orientation.

Signal/Signal-Info.plist

@@ -148,8 +148,6 @@
 	<key>UISupportedInterfaceOrientations</key>
 	<array>
 		<string>UIInterfaceOrientationPortrait</string>
-		<string>UIInterfaceOrientationLandscapeLeft</string>
-		<string>UIInterfaceOrientationLandscapeRight</string>
 	</array>
 	<key>UIViewControllerBasedStatusBarAppearance</key>
 	<true/>

Signal/src/ViewControllers/MenuActionsViewController.swift

@@ -93,7 +93,7 @@ class MenuActionsViewController: UIViewController, MenuActionSheetDelegate {
     // MARK: Orientation
 
     override public var supportedInterfaceOrientations: UIInterfaceOrientationMask {
-        return .allButUpsideDown
+        return DefaultUIInterfaceOrientationMask()
     }
 
     // MARK: Present / Dismiss animations

Signal/src/ViewControllers/OWSImagePickerController.swift

@@ -9,6 +9,6 @@ import Foundation
     // MARK: Orientation
 
     override public var supportedInterfaceOrientations: UIInterfaceOrientationMask {
-        return .allButUpsideDown
+        return DefaultUIInterfaceOrientationMask()
     }
 }

Signal/src/ViewControllers/ProfileViewController.m

@@ -624,7 +624,7 @@ NSString *const kProfileView_LastPresentedDate = @"kProfileView_LastPresentedDat
 - (UIInterfaceOrientationMask)supportedInterfaceOrientations
 {
     return (self.profileViewMode == ProfileViewMode_Registration ? UIInterfaceOrientationMaskPortrait
-                                                                 : UIInterfaceOrientationMaskAllButUpsideDown);
+                                                                 : DefaultUIInterfaceOrientationMask());
 }
 
 @end

Signal/src/ViewControllers/Registration/BackupRestoreViewController.swift

@@ -170,6 +170,6 @@ public class BackupRestoreViewController: OWSTableViewController {
     // MARK: Orientation
 
     public override var supportedInterfaceOrientations: UIInterfaceOrientationMask {
-        return .allButUpsideDown
+        return DefaultUIInterfaceOrientationMask()
     }
 }

SignalMessaging/ViewControllers/CountryCodeViewController.m

@@ -28,7 +28,7 @@
     [super loadView];
 
     self.shouldUseTheme = NO;
-    self.interfaceOrientationMask = UIInterfaceOrientationMaskAllButUpsideDown;
+    self.interfaceOrientationMask = DefaultUIInterfaceOrientationMask();
 
     self.view.backgroundColor = [UIColor whiteColor];
     self.title = NSLocalizedString(@"COUNTRYCODE_SELECT_TITLE", @"");

SignalMessaging/ViewControllers/OWSViewController.h

@@ -1,11 +1,15 @@
 //
-//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
+//  Copyright (c) 2019 Open Whisper Systems. All rights reserved.
 //
 
 #import <UIKit/UIKit.h>
 
 NS_ASSUME_NONNULL_BEGIN
 
+#define LANDSCAPE_ORIENTATION_ENABLED
+
+UIInterfaceOrientationMask DefaultUIInterfaceOrientationMask(void);
+
 @interface OWSViewController : UIViewController
 
 @property (nonatomic) BOOL shouldIgnoreKeyboardChanges;

SignalMessaging/ViewControllers/OWSViewController.m

@@ -8,6 +8,15 @@
 
 NS_ASSUME_NONNULL_BEGIN
 
+UIInterfaceOrientationMask DefaultUIInterfaceOrientationMask(void)
+{
+#ifdef LANDSCAPE_ORIENTATION_ENABLED
+    return UIInterfaceOrientationMaskAllButUpsideDown;
+#else
+    return UIInterfaceOrientationMaskPortrait;
+#endif
+}
+
 @interface OWSViewController ()
 
 @property (nonatomic, weak) UIView *bottomLayoutView;
@@ -185,7 +194,7 @@ NS_ASSUME_NONNULL_BEGIN
 
 - (UIInterfaceOrientationMask)supportedInterfaceOrientations
 {
-    return UIInterfaceOrientationMaskAllButUpsideDown;
+    return DefaultUIInterfaceOrientationMask();
 }
 
 @end