[Android] Introduce a Java wrapper for TemplateUrlService.

chrome/android/java/src/org/chromium/chrome/browser/search_engines/TemplateUrlService.java

Index: chrome/android/java/src/org/chromium/chrome/browser/search_engines/TemplateUrlService.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/search_engines/TemplateUrlService.java b/chrome/android/java/src/org/chromium/chrome/browser/search_engines/TemplateUrlService.java
new file mode 100644
index 0000000000000000000000000000000000000000..43b0edceb6841dbdd3a72aba2c3361933fd93c76
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/search_engines/TemplateUrlService.java
@@ -0,0 +1,118 @@
+// Copyright (c) 2013 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.search_engines;
+
+import org.chromium.base.CalledByNative;
+import org.chromium.base.ThreadUtils;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+
+/**
+ * Android wrapper of the TemplateUrlService which provides access from the Java
+ * layer.
+ *
+ * See chrome/browser/search_engines/template_url_service.h for more details.
+ */
+public class TemplateUrlService {
+
+    /**
+     * This listener will be notified when template url service is done laoding.
+     */
+    public interface LoadListener {
+        public abstract void onTemplateUrlServiceLoaded();
+    }
+
+    private static TemplateUrlService sService;

[nyquist, 2013/02/20 07:33:09]

Nit: Insert newline

[Yaron, 2013/02/21 21:39:15]

Done.

+    public static TemplateUrlService getInstance() {
+        ThreadUtils.assertOnUiThread();

[nyquist, 2013/02/20 07:33:09]

Maybe add to the class-level documentation that this class should only be
accessed on the UI thread?
Some of the methods assume that you only access it on the UI thread, whereas
others are protected by synchronized blocks (such as registering/unregistering
observers for the load).

For example, it is unclear whether isLoaded() can be called on a different
thread (in native land it inspects the internal field, so should only be called
from the correct thread).

[Yaron, 2013/02/21 21:39:15]

I decided to keep this simple and require all access form the main thread. Turns
out, it was only used from there, so prefer not to add extra threading logic
until needed

+        if (sService == null) {
+            sService = new TemplateUrlService();
+        }
+        return sService;
+    }
+
+    private TemplateUrlService() {
+        // Note that this technically leaks the native object, however, TemlateUrlService
+        // is a singleton that lives forever and there's no clean shutdown of Chrome on Android
+        mNativeTemplateUrlServiceAndroid = nativeInit();
+    }
+
+    public boolean isLoaded() {
+        return nativeIsLoaded(mNativeTemplateUrlServiceAndroid);
+    }
+
+    public void load() {
+        nativeLoad(mNativeTemplateUrlServiceAndroid);
+    }
+
+    /**
+     * Get the hash map of the localized search engines.
+     */
+    public HashMap<String,String>[] getLocalizedSearchEngines() {
+        return nativeGetLocalizedSearchEngines(mNativeTemplateUrlServiceAndroid);
+    }
+
+    private final int mNativeTemplateUrlServiceAndroid;

[nyquist, 2013/02/20 07:33:09]

Move final member fields above constructor

[Yaron, 2013/02/21 21:39:15]

Done.

+    private final List<LoadListener> mLoadListeners = new ArrayList<LoadListener>();
+
+    // Keys for localized search engines.
+    // MUST match static strings defined in template_url_service_android.cc
+    public static final String SEARCH_ENGINE_ID = "searchEngineId";

[nyquist, 2013/02/20 07:33:09]

Move these up to the top of the class, before any member methods or fields.

[Yaron, 2013/02/21 21:39:15]

Done.

+    public static final String SEARCH_ENGINE_URL = "searchEngineUrl";
+    public static final String SEARCH_ENGINE_KEYWORD = "searchEngineKeyword";
+    public static final String SEARCH_ENGINE_SHORT_NAME = "searchEngineShortName";
+
+    /**
+     * Called from native when template URL service is done loading.
+     */
+    @CalledByNative
+    private void templateUrlServiceLoaded() {
+        synchronized (mLoadListeners) {

[bulach, 2013/02/20 14:41:25]

so the listeners will be potentially called on a different thread than the one
they were registered? worth a comment in 26 above..

[Yaron, 2013/02/21 21:39:15]

Changed to only ui thread.

+            for (LoadListener listener : mLoadListeners) {
+                listener.onTemplateUrlServiceLoaded();
+            }
+        }
+    }
+
+    public int getSearchEngine() {
+        return nativeGetSearchEngine(mNativeTemplateUrlServiceAndroid);
+    }
+
+    public void setSearchEngine(int selectedIndex) {
+        nativeSetSearchEngine(mNativeTemplateUrlServiceAndroid, selectedIndex);
+    }
+
+    /**
+     * Registers a listener for the TEMPLATE_URL_SERVICE_LOADED notification.
+     */
+    public void registerLoadListener(LoadListener listener) {
+        synchronized (mLoadListeners) {
+            assert !mLoadListeners.contains(listener);
+            mLoadListeners.add(listener);
+        }
+    }
+
+    /**
+     * Unregisters a listener for the TEMPLATE_URL_SERVICE_LOADED notification.
+     */
+    public void unregisterLoadListener(LoadListener listener) {
+        synchronized (mLoadListeners) {
+            assert (mLoadListeners.size() > 0);
+            assert (mLoadListeners.contains(listener));
+            mLoadListeners.remove(listener);
+        }
+    }
+
+    private native int nativeInit();
+    private native void nativeLoad(int nativeTemplateUrlServiceAndroid);
+    private native boolean nativeIsLoaded(int nativeTemplateUrlServiceAndroid);
+    private native HashMap<String,String>[] nativeGetLocalizedSearchEngines(
+            int nativeTemplateUrlServiceAndroid);
+    private native void nativeSetSearchEngine(int nativeTemplateUrlServiceAndroid,
+            int selectedIndex);
+    private native int nativeGetSearchEngine(int nativeTemplateUrlServiceAndroid);
+}