Added TextWatcher for empty input edit text

> Disable OK button when filename edit text is empty, otherwise reset to enabled.

Bug: 924751
Change-Id: I8138fe41a65c69f5f9e3ac59c2483fdd6667d09f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1548371Reviewed-by: David Trainor <dtrainor@chromium.org>
Reviewed-by: Shakti Sahu <shaktisahu@chromium.org>
Commit-Queue: Hesen Zhang <hesen@google.com>
Cr-Commit-Position: refs/heads/master@{#649703}

chrome/android/java/src/org/chromium/chrome/browser/download/home/rename/RenameDialogCoordinator.java

@@ -42,6 +42,10 @@ public class RenameDialogCoordinator {
                         .build();
         mOnClickEventCallback = onClickCallback;
         mOnDismissEventCallback = dismissCallback;
+
+        mRenameDialogCustomView.setEmptyInputObserver((result) -> {
+            mRenameDialogModel.set(ModalDialogProperties.POSITIVE_BUTTON_DISABLED, result);
+        });
     }
 
     public void destroy() {

chrome/android/java/src/org/chromium/chrome/browser/download/home/rename/RenameDialogCustomView.java

@@ -7,13 +7,16 @@ package org.chromium.chrome.browser.download.home.rename;
 import static android.content.Context.INPUT_METHOD_SERVICE;
 
 import android.content.Context;
+import android.text.Editable;
 import android.text.TextUtils;
+import android.text.TextWatcher;
 import android.util.AttributeSet;
 import android.view.View;
 import android.view.inputmethod.InputMethodManager;
 import android.widget.ScrollView;
 import android.widget.TextView;
 
+import org.chromium.base.Callback;
 import org.chromium.chrome.browser.widget.AlertDialogEditText;
 import org.chromium.chrome.download.R;
 import org.chromium.components.offline_items_collection.RenameResult;
@@ -24,6 +27,7 @@ import org.chromium.components.offline_items_collection.RenameResult;
 public class RenameDialogCustomView extends ScrollView {
     private TextView mSubtitleView;
     private AlertDialogEditText mFileName;
+    private Callback</*Empty*/ Boolean> mEmptyFileNameObserver;
 
     public RenameDialogCustomView(Context context, AttributeSet attrs) {
         super(context, attrs);
@@ -35,6 +39,26 @@ public class RenameDialogCustomView extends ScrollView {
         super.onFinishInflate();
         mSubtitleView = findViewById(R.id.subtitle);
         mFileName = findViewById(R.id.file_name);
+        mFileName.addTextChangedListener(new TextWatcher() {
+            @Override
+            public void beforeTextChanged(CharSequence s, int start, int count, int after) {}
+
+            @Override
+            public void onTextChanged(CharSequence s, int start, int before, int count) {}
+
+            @Override
+            public void afterTextChanged(Editable s) {
+                if (mEmptyFileNameObserver == null) return;
+                mEmptyFileNameObserver.onResult(getTargetName().isEmpty());
+            }
+        });
+    }
+
+    /**
+     * @param callback Callback to run when edit text is empty.
+     */
+    public void setEmptyInputObserver(Callback<Boolean> callback) {
+        mEmptyFileNameObserver = callback;
     }
 
     /**

chrome/android/java/src/org/chromium/chrome/browser/download/home/rename/RenameDialogManager.java

@@ -158,9 +158,6 @@ public class RenameDialogManager {
         if (isPositiveButton) {
             mLastAttemptedName = mRenameDialogCoordinator.getCurSuggestedName();
 
-            // TODO(hesen): Have a TextWatcher on the input, and disable OK button if it's empty.
-            if (TextUtils.isEmpty(mLastAttemptedName)) return;
-
             if (TextUtils.equals(mLastAttemptedName, mOriginalName)) {
                 processDialogState(RenameDialogState.RENAME_DIALOG_CANCEL,
                         DialogDismissalCause.POSITIVE_BUTTON_CLICKED);