hook up onScroll event to RCTTextInputComponentView

Summary:
fixing oncall issue: https://fb.workplace.com/groups/rn.support/permalink/7241260632589156/

in this diff, we hook up the event emitter onScroll event to the native text input view

Changelog: [Internal]

Reviewed By: sammy-SC

Differential Revision: D32523146

fbshipit-source-id: d8035deacc8a511577a6fb892ac55c9e07b14392

React/Fabric/Mounting/ComponentViews/TextInput/RCTTextInputComponentView.mm

@@ -394,6 +394,15 @@ - (void)textInputDidChangeSelection
   }
 }
 
+#pragma mark - RCTBackedTextInputDelegate (UIScrollViewDelegate)
+
+- (void)scrollViewDidScroll:(UIScrollView *)scrollView
+{
+  if (_eventEmitter) {
+    std::static_pointer_cast<TextInputEventEmitter const>(_eventEmitter)->onScroll([self _textInputMetrics]);
+  }
+}
+
 #pragma mark - Native Commands
 
 - (void)handleCommand:(const NSString *)commandName args:(const NSArray *)args
@@ -499,6 +508,22 @@ - (TextInputMetrics)_textInputMetrics
   metrics.text = RCTStringFromNSString(_backedTextInputView.attributedText.string);
   metrics.selectionRange = [self _selectionRange];
   metrics.eventCount = _mostRecentEventCount;
+
+  CGPoint contentOffset = _backedTextInputView.contentOffset;
+  metrics.contentOffset = {contentOffset.x, contentOffset.y};
+
+  UIEdgeInsets contentInset = _backedTextInputView.contentInset;
+  metrics.contentInset = {contentInset.left, contentInset.top, contentInset.right, contentInset.bottom};
+
+  CGSize contentSize = _backedTextInputView.contentSize;
+  metrics.contentSize = {contentSize.width, contentSize.height};
+
+  CGSize layoutMeasurement = _backedTextInputView.bounds.size;
+  metrics.layoutMeasurement = {layoutMeasurement.width, layoutMeasurement.height};
+
+  CGFloat zoomScale = _backedTextInputView.zoomScale;
+  metrics.zoomScale = zoomScale;
+
   return metrics;
 }