webapps: introduce helper class to store extended set of data

chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappDataStorage.java

+// 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.webapps;
+
+import android.content.Context;
+import android.content.SharedPreferences;
+import android.graphics.Bitmap;
+import android.graphics.BitmapFactory;
+import android.text.TextUtils;
+import android.util.Base64;
+
+import java.io.ByteArrayOutputStream;
+
+/**
+ * This is a class used to store data about an installed webapp.
+ */
+public class WebappDataStorage {
+
+    private final SharedPreferences mPreferences;
+
+    private WebappDataStorage(Context context, String webappId) {
+        mPreferences = context.getSharedPreferences("webapp_" + webappId,
+            Context.MODE_PRIVATE);
+    }
+
+    public static WebappDataStorage open(Context context, String webappId) {
+        return new WebappDataStorage(context, webappId);
+    }
+
+    public Bitmap getSplashIcon() {

[mlamouri (slow - plz ping), 2015/08/13 11:21:01]

Is that call synchronous? Is that going to slow down the startup?

[Lalit Maganti, 2015/08/18 12:45:45]

Yes and yes. I've made it async and introduced callbacks.

+        String icon = mPreferences.getString("splash_icon", "");
+        Bitmap decodedIcon = null;
+        if (!TextUtils.isEmpty(icon)) {
+            byte[] decoded = Base64.decode(icon, Base64.DEFAULT);
+            decodedIcon = BitmapFactory.decodeByteArray(decoded, 0, decoded.length);
+        }
+        return decodedIcon;
+    }
+
+    public WebappDataStorage putSplashIcon(Bitmap icon) {
+        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
+        icon.compress(Bitmap.CompressFormat.PNG, 100, byteArrayOutputStream);
+        byte[] byteArray = byteArrayOutputStream.toByteArray();
+        mPreferences.edit()
+            .putString("splash_icon", Base64.encodeToString(byteArray, Base64.DEFAULT))
+            .commit();

[gone, 2015/08/12 22:32:32]

you probably want to use apply() instead.  commit() is synchronous.

[Lalit Maganti, 2015/08/18 12:45:46]

Done.

+        return this;
+    }
+}