Add custom dimension provider to RCTDeviceInfo (#54107)

Summary:
Pull Request resolved: #54107

Adds a dimension provider override to RCTDeviceInfo.

Changelog: [Internal]

Reviewed By: javache

Differential Revision: D84131733

fbshipit-source-id: 2419bcb9a23486eee61f203414084d5105a091f8

Author: sbuggay

packages/react-native/React/CoreModules/RCTDeviceInfo.h

@@ -11,4 +11,6 @@
 
 @interface RCTDeviceInfo : NSObject <RCTBridgeModule>
 
+- (instancetype)initWithDimensionsProvider:(NSDictionary * (^)(void))dimensionsProvider;
+
 @end

packages/react-native/React/CoreModules/RCTDeviceInfo.mm

@@ -32,6 +32,7 @@ @implementation RCTDeviceInfo {
   NSDictionary *_constants;
 
   __weak UIWindow *_applicationWindow;
+  NSDictionary * (^_dimensionsProvider)(void);
 }
 
 static NSString *const kFrameKeyPath = @"frame";
@@ -49,6 +50,14 @@ - (instancetype)init
   return self;
 }
 
+- (instancetype)initWithDimensionsProvider:(NSDictionary * (^)(void))dimensionsProvider
+{
+  if (self = [self init]) {
+    _dimensionsProvider = dimensionsProvider;
+  }
+  return self;
+}
+
 - (void)observeValueForKeyPath:(NSString *)keyPath
                       ofObject:(id)object
                         change:(NSDictionary *)change
@@ -199,6 +208,15 @@ static BOOL RCTIsIPhoneNotched()
 
 - (NSDictionary *)_exportedDimensions
 {
+  // if a window size provider has been set, use that. If nil is returned from the provider
+  // it will fall back to the default behavior.
+  if (_dimensionsProvider != nil) {
+    auto dimensions = _dimensionsProvider();
+    if (dimensions != nil) {
+      return dimensions;
+    }
+  }
+
   RCTAssert(!_invalidated, @"Failed to get exported dimensions: RCTDeviceInfo has been invalidated");
   RCTAssert(_moduleRegistry, @"Failed to get exported dimensions: RCTModuleRegistry is nil");
   RCTAccessibilityManager *accessibilityManager =