Add a custome edittext that encapsulates the error message logic

chrome/android/java/src/org/chromium/chrome/browser/widget/EmptyAlertEditText.java

Index: chrome/android/java/src/org/chromium/chrome/browser/widget/EmptyAlertEditText.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/widget/EmptyAlertEditText.java b/chrome/android/java/src/org/chromium/chrome/browser/widget/EmptyAlertEditText.java
new file mode 100644
index 0000000000000000000000000000000000000000..aa13cfddddd68633a87a456174a1fd5c82330ced
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/widget/EmptyAlertEditText.java
@@ -0,0 +1,69 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.chrome.browser.widget;
+
+import android.content.Context;
+import android.content.res.TypedArray;
+import android.support.v7.widget.AppCompatEditText;
+import android.text.Editable;
+import android.text.TextWatcher;
+import android.util.AttributeSet;
+
+import org.chromium.chrome.R;
+
+/**
+ * An EditText that shows an alert message when the content is empty.
+ */
+public class EmptyAlertEditText extends AppCompatEditText {
+
+    private String mAlertMessage;
+
+    /**
+     * Constructor for inflating from XML.
+     */
+    public EmptyAlertEditText(Context context, AttributeSet attrs) {
+        super(context, attrs);
+        final TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.EmptyAlertEditText);
+        int resId = a.getResourceId(R.styleable.EmptyAlertEditText_alertMessage, 0);
+        if (resId != 0) mAlertMessage = context.getResources().getString(resId);
+        a.recycle();
+    }
+
+    @Override
+    protected void onFinishInflate() {
+        super.onFinishInflate();
+        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 (s.length() != 0 && getError() != null) setError(null);
+            }
+        });
+    }
+
+    /**
+     * Sets the alert message to be shown when the text content is empty.
+     */
+    public void setAlertMessage(String message) {
+        mAlertMessage = message;
+    }
+
+    /**
+     * Checks whether the content is empty. If empty, an alert message will be shown.
+     * @return Whether the content is empty.
+     */
+    public boolean validate() {
+        if (getText().length() == 0) {
+            setError(mAlertMessage);
+            return true;
+        }
+        return false;
+    }
+}