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..3487beb46a71c9e1531ee85869dcb9d1550732d6
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/webapps/ManifestUpgradeDetector.java
@@ -0,0 +1,201 @@
+// 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 android.graphics.Bitmap;
+
+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.ShortcutHelper;
+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 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) {
+        mTab = tab;
+        tab.addObserver(this);
+        mWebappInfo = info;
+        mNativePointer = nativeInitialize(mTab.getWebContents());
+    }
+
+    /**
+     * Updates the status of the native ManifestUpgradeDetector to start the web manifest resources
+     * fetching pipeline.
+     */
+    public void start() {
+        nativeStart(mNativePointer);
+    }
+
+    /**
+     * Puts the object in a state where it is safe to be destroyed.
+     */
+    public void destroy() {
+        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,
+            Bitmap icon,
+            String[] iconUrls, int displayMode, int orientation, long themeColor,
+            long backgroundColor) {
+        final WebappInfo newInfo = WebappInfo.create(mWebappInfo.id(), startUrl,
+                ShortcutHelper.encodeBitmapAsString(icon), name, shortName,
+                displayMode, orientation, mWebappInfo.source(), themeColor, backgroundColor,
+                false, mWebappInfo.webApkPackageName());
+        final Set<String> iconUrlSet = new HashSet<String>(Arrays.asList(iconUrls));

[pkotwicz, 2016/07/12 01:23:48]

This if() statement should be in its own function. It took me a while to
remember why we were checking only some of WebappInfo's attributes.

[Xi Han, 2016/07/12 20:53:41]

Done.

+        if (!mWebappInfo.uri().toString().equals(startUrl)
+                || !mWebappInfo.name().equals(newInfo.name())
+                || mWebappInfo.backgroundColor() != newInfo.backgroundColor()) {
+            mWebappInfo = newInfo;
+            notifyObserver(true, true, iconUrlSet);
+            return;
+        }

[pkotwicz, 2016/07/12 01:23:48]

Should we always call WebappDataStorage#updateFromWebappInfo() regardless of
whether the Web Manifest has changed? I think this will make things simpler

[Xi Han, 2016/07/12 20:53:41]

We could, yes, then we don't need to check all those non-critical resources.
Updated.

+        WebappRegistry.getWebappDataStorage(ContextUtils.getApplicationContext(), mWebappInfo.id(),
+                new WebappRegistry.FetchWebappDataStorageCallback() {
+                    @Override
+                    public void onWebappDataStorageRetrieved(WebappDataStorage storage) {
+                        onWebappDataRetrieved(storage, newInfo, iconUrlSet);
+                    }
+                });
+    }
+
+    /**
+     * Checks whether the new fetched resources match the ones stored in the SharedPreference.
+     */
+    private void onWebappDataRetrieved(WebappDataStorage storage, WebappInfo newInfo,
+            Set<String> iconUrlSet) {
+        boolean isUpgraded = false;
+        boolean updateSharedPreference = false;
+
+        Set<String> cachedIconUrlsSet = storage.getIconUrls();
+        boolean isIconSame = checkIcon(ShortcutHelper.decodeBitmapFromString(
+                storage.getIcon()), newInfo.icon());
+        if (cachedIconUrlsSet == null) {
+            // If icon urls haven't been cached, whether to re-mint WebAPK depends on
+            // other resources, but will update the SharedPreference.
+            notifyObserver(!isIconSame, true, iconUrlSet);
+            return;
+        }
+        boolean isIconUrlSetSame = checkIconUrlSet(cachedIconUrlsSet, iconUrlSet);
+        if (!isIconSame || !isIconUrlSetSame) {
+            isUpgraded = true;
+        }
+        if (isUpgraded || !mWebappInfo.shortName().equals(newInfo.shortName())
+                || mWebappInfo.displayMode() != newInfo.displayMode()
+                || mWebappInfo.orientation() != newInfo.orientation()
+                || mWebappInfo.themeColor() != newInfo.themeColor()) {
+            updateSharedPreference = true;
+        }
+        if (isUpgraded || updateSharedPreference) {
+            mWebappInfo = newInfo;
+        }
+        notifyObserver(isUpgraded, updateSharedPreference, iconUrlSet);
+    }
+
+    /**
+     * 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);
+    }
+
+    /**
+     * Returns whether two icons are the same.
+     */
+    private boolean checkIcon(Bitmap icon, Bitmap anotherIcon) {
+        if (icon == null) return anotherIcon == null;
+        return icon.sameAs(anotherIcon);
+    }
+
+    private void notifyObserver(boolean isUpgraded, boolean updateSharedPreference,
+            Set<String> iconUrls) {
+        mObserver.onManifestAvaliable(isUpgraded, !isUpgraded && !updateSharedPreference ? null
+                : mWebappInfo, iconUrls);
+    }
+
+    private native long nativeInitialize(WebContents webContents);
+    private native void nativeReplaceWebContents(long nativeManifestUpgradeDetector,
+            WebContents webContents);
+    private native void nativeDestroy(long nativeManifestUpgradeDetector);
+    private native void nativeStart(long nativeManifestUpgradeDetector);
+}