Avoid eating clicks/taps into ScrollView when using physical keyboard (facebook#30374)

Summary:
This is an extension of facebook#29798 which was reverted due to cases where the soft keyboard could not be dismissed.

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[General] [Fixed] - Avoid eating clicks/taps into ScrollView when using physical keyboard

Pull Request resolved: facebook#30374

Test Plan: Validated with iOS simulator that taps on default ScrollView will dismiss soft keyboard and be eaten if open, but taps are not eaten when emulating a connected physical keyboard.

Reviewed By: kacieb

Differential Revision: D24935077

Pulled By: lyahdav

fbshipit-source-id: 19d9cf64547e40a35f9363896e3abbdccb95b546

Author: NickGerleman

Libraries/Components/ScrollResponder.js

@@ -187,7 +187,7 @@ const ScrollResponderMixin = {
 
     if (
       this.props.keyboardShouldPersistTaps === 'handled' &&
-      currentlyFocusedInput != null &&
+      this.scrollResponderKeyboardIsDismissible() &&
       e.target !== currentlyFocusedInput
     ) {
       return true;
@@ -224,7 +224,6 @@ const ScrollResponderMixin = {
     // and a new touch starts with a non-textinput target (in which case the
     // first tap should be sent to the scroll view and dismiss the keyboard,
     // then the second tap goes to the actual interior view)
-    const currentlyFocusedTextInput = TextInputState.currentlyFocusedInput();
     const {keyboardShouldPersistTaps} = this.props;
     const keyboardNeverPersistTaps =
       !keyboardShouldPersistTaps || keyboardShouldPersistTaps === 'never';
@@ -241,7 +240,7 @@ const ScrollResponderMixin = {
 
     if (
       keyboardNeverPersistTaps &&
-      currentlyFocusedTextInput != null &&
+      this.scrollResponderKeyboardIsDismissible() &&
       e.target != null &&
       !TextInputState.isTextInput(e.target)
     ) {
@@ -251,6 +250,31 @@ const ScrollResponderMixin = {
     return false;
   },
 
+  /**
+   * Do we consider there to be a dismissible soft-keyboard open?
+   */
+  scrollResponderKeyboardIsDismissible: function(): boolean {
+    const currentlyFocusedInput = TextInputState.currentlyFocusedInput();
+
+    // We cannot dismiss the keyboard without an input to blur, even if a soft
+    // keyboard is open (e.g. when keyboard is open due to a native component
+    // not participating in TextInputState). It's also possible that the
+    // currently focused input isn't a TextInput (such as by calling ref.focus
+    // on a non-TextInput).
+    const hasFocusedTextInput =
+      currentlyFocusedInput != null &&
+      TextInputState.isTextInput(currentlyFocusedInput);
+
+    // Even if an input is focused, we may not have a keyboard to dismiss. E.g
+    // when using a physical keyboard. Ensure we have an event for an opened
+    // keyboard, except on Android where setting windowSoftInputMode to
+    // adjustNone leads to missing keyboard events.
+    const softKeyboardMayBeOpen =
+      this.keyboardWillOpenTo != null || Platform.OS === 'android';
+
+    return hasFocusedTextInput && softKeyboardMayBeOpen;
+  },
+
   /**
    * Invoke this from an `onResponderReject` event.
    *
@@ -325,7 +349,7 @@ const ScrollResponderMixin = {
     if (
       this.props.keyboardShouldPersistTaps !== true &&
       this.props.keyboardShouldPersistTaps !== 'always' &&
-      currentlyFocusedTextInput != null &&
+      this.scrollResponderKeyboardIsDismissible() &&
       e.target !== currentlyFocusedTextInput &&
       !this.state.observedScrollSinceBecomingResponder &&
       !this.state.becameResponderWhileAnimating