Add a basic UI to the Android Blimp client.

blimp/client/android/java/src/org/chromium/blimp/toolbar/UrlBar.java

Index: blimp/client/android/java/src/org/chromium/blimp/toolbar/UrlBar.java
diff --git a/blimp/client/android/java/src/org/chromium/blimp/toolbar/UrlBar.java b/blimp/client/android/java/src/org/chromium/blimp/toolbar/UrlBar.java
new file mode 100644
index 0000000000000000000000000000000000000000..9f019280ba614c2963f019c4b42c211b1c924162
--- /dev/null
+++ b/blimp/client/android/java/src/org/chromium/blimp/toolbar/UrlBar.java
@@ -0,0 +1,81 @@
+// 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.blimp.toolbar;
+
+import android.content.Context;
+import android.util.AttributeSet;
+import android.view.KeyEvent;
+import android.view.View;
+import android.view.View.OnKeyListener;
+import android.widget.EditText;
+
+import org.chromium.base.ObserverList;
+import org.chromium.ui.UiUtils;
+
+/**
+ * A {@link View} that a;lows users to enter text and URLs.
+ */
+public class UrlBar extends EditText implements OnKeyListener {
+    /**
+     * An observer that gets notified of relevant URL bar text changes.
+     */
+    public interface UrlBarObserver {
+        /**
+         * Will be called when the user presses enter after typing something into this
+         * {@link EditText}.
+         * @param text The new text the user entered.
+         */
+        void onNewTextEntered(String text);
+    }
+
+    private ObserverList<UrlBarObserver> mObservers = new ObserverList<UrlBarObserver>();

[nyquist, 2015/11/09 01:58:45]

Nit: final

[David Trainor- moved to gerrit, 2015/11/09 17:17:45]

Done.

+
+    /**
+     * Builds a new {@link UrlBar}.
+     * @param context A {@link Context} instance.
+     * @param attrs   An {@link AttributeSet} instance.
+     */
+    public UrlBar(Context context, AttributeSet attrs) {
+        super(context, attrs);
+        setOnKeyListener(this);
+    }
+
+    /**
+     * @return The current text of this {@link EditText}.  Guaranteed to be not {@code null}.
+     */
+    public String getQueryText() {
+        return getEditableText() != null ? getEditableText().toString() : "";

[nyquist, 2015/11/09 01:58:45]

Optional nit: Flip the != to have the positive case first?

[David Trainor- moved to gerrit, 2015/11/09 17:17:45]

Done.

+    }
+
+    /**
+     * @param observer An {@link UrlBarObserver} that will be notified of future text entries.
+     */
+    public void addUrlBarObserver(UrlBarObserver observer) {
+        mObservers.addObserver(observer);
+    }
+
+    /**
+     * @param observer An {@link UrlBarObserver} that will no longer be notified of future text
+     *                 entries.
+     */
+    public void removeUrlBarObserver(UrlBarObserver observer) {
+        mObservers.removeObserver(observer);
+    }
+
+    // OnKeyListener interface.
+    @Override
+    public boolean onKey(View view, int keyCode, KeyEvent event) {
+        if (event.getAction() == KeyEvent.ACTION_UP
+                && (event.getKeyCode() == KeyEvent.KEYCODE_ENTER
+                || event.getKeyCode() == KeyEvent.KEYCODE_NUMPAD_ENTER)) {
+            UiUtils.hideKeyboard(view);
+            clearFocus();
+            for (UrlBarObserver observer : mObservers) {
+                observer.onNewTextEntered(getQueryText());
+            }
+        }
+        return false;
+    }
+}