Introduce ManifestUpgradeDetector for WebAPK to detect web manifest changes.

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

Index: chrome/android/java/src/org/chromium/chrome/browser/webapps/ManifestUpgradeDetector.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/webapps/ManifestUpgradeDetector.java b/chrome/android/java/src/org/chromium/chrome/browser/webapps/ManifestUpgradeDetector.java
new file mode 100644
index 0000000000000000000000000000000000000000..1515b41495329a6a7bb92dabe0ced6027809e871
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/webapps/ManifestUpgradeDetector.java
@@ -0,0 +1,185 @@
+// Copyright 2016 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 org.chromium.base.CommandLine;
+import org.chromium.base.ContextUtils;
+import org.chromium.base.VisibleForTesting;
+import org.chromium.base.annotations.CalledByNative;
+import org.chromium.chrome.browser.ChromeSwitches;
+import org.chromium.chrome.browser.tab.EmptyTabObserver;
+import org.chromium.chrome.browser.tab.Tab;
+import org.chromium.content_public.browser.WebContents;
+
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ * This class interacts with c++ to detect whether resources in web manifest of a WebAPK has been
+ * updated.
+ */
+public class ManifestUpgradeDetector extends EmptyTabObserver {
+    private long mNativePointer;
+    private final Tab mTab;
+    private WebappInfo mWebappInfo;
+    private Observer mObserver;
+    private static Boolean sIsEnabled;
+    private boolean mIsInitialized;
+
+    private static final String TAG = "cr_UpgradeDetector";
+
+    /** Observes the data fetching pipeline. */
+    public interface Observer {
+        /** Called when the web manifest of the page is available and the icon has been
+         *  downloaded. */
+        void onManifestAvaliable(boolean isUpgraded, WebappInfo newInfo, Set<String> iconUrls);
+    }
+
+    /**
+     * Sets the observer.
+     */
+    public void setManifestUpgradeDetectorObserver(Observer observer) {
+        mObserver = observer;
+    }
+
+    public ManifestUpgradeDetector(Tab tab, WebappInfo info) {

[pkotwicz, 2016/07/13 01:08:19]

Can the observer be passed into the constructor?

[Xi Han, 2016/07/13 19:25:14]

Done.

+        mTab = tab;
+        tab.addObserver(this);
+        mWebappInfo = info;
+        String webManifestUrl = info.webManifestUrl();
+        if (webManifestUrl == null || webManifestUrl.isEmpty()) return;
+        mNativePointer = nativeInitialize(mTab.getWebContents(), webManifestUrl);
+        mIsInitialized = true;
+    }
+
+    /**
+     * Updates the status of the native ManifestUpgradeDetector to start the web manifest resources
+     * fetching pipeline.
+     */
+    public void start() {
+        if (mIsInitialized) {
+            nativeStart(mNativePointer);
+        }
+    }
+
+    /**
+     * Puts the object in a state where it is safe to be destroyed.
+     */
+    public void destroy() {
+        if (mIsInitialized) {
+            nativeDestroy(mNativePointer);
+        }
+
+        mObserver = null;
+        mNativePointer = 0;
+    }
+
+    @Override
+    public void onWebContentsSwapped(Tab tab, boolean didStartLoad,
+            boolean didFinishLoad) {
+        updatePointers(tab);
+    }
+
+    @Override
+    public void onContentChanged(Tab tab) {
+        updatePointers(tab);
+    }
+
+    /**
+     * Updates which WebContents the native ManifestUpgradeDetector is monitoring.
+     */
+    private void updatePointers(Tab tab) {
+        nativeReplaceWebContents(mNativePointer, tab.getWebContents());
+    }
+
+    /**
+     * Returns whether to enable ManifestUpgradeDetector.
+     */
+    public static boolean isEnabled() {
+        if (sIsEnabled == null) {
+            sIsEnabled = CommandLine.getInstance().hasSwitch(ChromeSwitches.ENABLE_WEBAPK);
+        }
+        return sIsEnabled;
+    }
+
+    /** Enables or disables the web manifest upgrade detector for testing. */
+    @VisibleForTesting
+    public static void setIsEnabledForTesting(boolean state) {
+        sIsEnabled = state;
+    }
+
+    /**
+     * Checks whether the new fetched resources match the ones of the current WebAppInfo.
+     * The changes of start Url, name, background color and so on will lead to request
+     * updating the installed WebAPK.
+     */
+    @CalledByNative
+    private void onDataAvailable(String startUrl, String name, String shortName,
+            String[] iconUrls, int displayMode, int orientation, long themeColor,
+            long backgroundColor) {
+        final WebappInfo newInfo = WebappInfo.create(mWebappInfo.id(), startUrl,
+                null, name, shortName, displayMode, orientation, mWebappInfo.source(),
+                themeColor, backgroundColor, false, mWebappInfo.webApkPackageName(),
+                mWebappInfo.webManifestUrl());

[pkotwicz, 2016/07/13 01:08:19]

We need to validate that the new WebappInfo is WebAPK-compatible. For instance
the new short_name might be empty. Doing this checking will probably be easier
once https://codereview.chromium.org/2050933002/ lands. I am OK if you file
crbug and put a comment for now.

[Xi Han, 2016/07/13 19:25:14]

Done.

+        final Set<String> iconUrlSet = new HashSet<String>(Arrays.asList(iconUrls));
+        if (requireUpgrade(startUrl, newInfo)) {
+            mWebappInfo = newInfo;
+            notifyObserver(true, iconUrlSet);
+            return;
+        }
+        mWebappInfo = newInfo;
+        WebappRegistry.getWebappDataStorage(ContextUtils.getApplicationContext(), mWebappInfo.id(),
+                new WebappRegistry.FetchWebappDataStorageCallback() {
+                    @Override
+                    public void onWebappDataStorageRetrieved(WebappDataStorage storage) {
+                        onWebappDataRetrieved(storage, iconUrlSet);
+                    }
+                });
+    }
+
+    /**
+     * Checks whether the new fetched resources match the ones stored in the SharedPreference.
+     */
+    private void onWebappDataRetrieved(WebappDataStorage storage, Set<String> iconUrlSet) {
+        Set<String> cachedIconUrlsSet = storage.getIconUrls();
+        // If icon urls haven't been cached, whether to re-mint WebAPK depends on
+        // other resources.
+        boolean isUpgraded = cachedIconUrlsSet == null ? false
+                : !checkIconUrlSet(cachedIconUrlsSet, iconUrlSet);
+
+        notifyObserver(isUpgraded, iconUrlSet);
+    }
+
+    /**
+     * Checks whether attributes, like start Url, app name, background color, are changed.
+     * {@link mWebappInfo} keeps the latest version of these attributes, so no metadata query is
+     * needed. These attributes' changes require to re-mint a WebAPK.
+     */
+    private boolean requireUpgrade(String startUrl, WebappInfo newInfo) {
+        return !mWebappInfo.uri().toString().equals(startUrl)
+                || !mWebappInfo.name().equals(newInfo.name())

[pkotwicz, 2016/07/13 01:08:20]

We should check whether the "short_name" is different not the "name" because it
is the "short_name" which is used for the app's name in the app list

[Xi Han, 2016/07/13 19:25:14]

Done.

+                || mWebappInfo.backgroundColor() != newInfo.backgroundColor();
+    }
+
+    /**
+     * Returns whether two icon url sets are equal.
+     */
+    private boolean checkIconUrlSet(Set<String> set, Set<String> anotherSet) {
+        if (set == null) return anotherSet == null;
+        return anotherSet != null && set.size() == anotherSet.size()
+                && set.containsAll(anotherSet);
+    }
+
+    private void notifyObserver(boolean isUpgraded, Set<String> iconUrls) {
+        mObserver.onManifestAvaliable(isUpgraded, mWebappInfo, iconUrls);
+    }
+
+    private native long nativeInitialize(WebContents webContents, String webManifestUrl);
+    private native void nativeReplaceWebContents(long nativeManifestUpgradeDetector,
+            WebContents webContents);
+    private native void nativeDestroy(long nativeManifestUpgradeDetector);
+    private native void nativeStart(long nativeManifestUpgradeDetector);
+}