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..d99e4e30727f5338901425976e0ed866b9787840
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/webapps/ManifestUpgradeDetector.java
@@ -0,0 +1,176 @@
+// 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.content.pm.ApplicationInfo;
+import android.content.pm.PackageManager;
+import android.net.Uri;
+
+import org.chromium.base.CommandLine;
+import org.chromium.base.ContextUtils;
+import org.chromium.base.Log;
+import org.chromium.base.VisibleForTesting;
+import org.chromium.base.annotations.CalledByNative;
+import org.chromium.chrome.browser.tab.EmptyTabObserver;
+import org.chromium.chrome.browser.tab.Tab;
+import org.chromium.content_public.browser.WebContents;
+
+/**
+ * This class interacts with C++ to detect whether resources in web manifest of a WebAPK have been
+ * updated.
+ */
+public class ManifestUpgradeDetector extends EmptyTabObserver {
+    @VisibleForTesting
+    public static final String SWITCH_DO_NOT_USE_META_DATA_FROM_WEBAPK_FOR_TESTING =

[pkotwicz, 2016/07/25 17:35:53]

Nit: Remove "switch-" from switch

[Xi Han, 2016/07/25 20:01:37]

Done.

+            "switch-do-not-use-meta-data-from-webapk-for-testing";
+    /**
+     * The names of <meta-data> in the WebAPK's AndroidManifest.xml whose values are needed to
+     * determine whether a WebAPK needs to be upgraded but which are not present in
+     * {@link WebappInfo}. The names must stay in sync with
+     * {@linkorg.chromium.webapk.lib.runtime_library.HostBrowserLauncher}.
+     */
+    private static final String META_DATA_START_URL = "startUrl";
+
+    /** Pointer to the native side ManifestUpgradeDetector. */
+    private long mNativePointer;
+
+    /** The tab that is being observed. */
+    private final Tab mTab;
+
+    private WebappInfo mWebappInfo;
+    private String mStartUrl;
+
+    private static final String TAG = "cr_UpgradeDetector";
+
+    public ManifestUpgradeDetector(Tab tab, WebappInfo info) {
+        mTab = tab;
+        mWebappInfo = info;
+    }
+
+    @VisibleForTesting
+    public void setMetadataForTesting(String startUrl) {

[Yaron, 2016/07/25 15:55:02]

If you rename this to: overrideMetadataForTesting and have it set a bool, you
can remove the dependency on CommandLine and the new switch

[Xi Han, 2016/07/25 20:01:37]

Done.

[Yaron, 2016/07/25 22:29:06]

I meant that you can collapse these two into one function. if you are setting
the start url for testing, you are implicitly overriding the metadata (since
that's where startUrl would typically come from). But I guess if you re-use a
detector across tests it could leak more easily so I'm fine with it.

[Xi Han, 2016/07/27 00:38:15]

Acknowledged.

+        mStartUrl = startUrl;
+    }
+
+    /**
+     * Starts fetching the web manifest resources.
+     */
+    public void start() {
+        if (mWebappInfo.webManifestUri() == null
+                || mWebappInfo.webManifestUri().equals(Uri.EMPTY)) {
+            return;
+        }
+
+        if (mNativePointer != 0) return;
+
+        getMetaDataFromAndroidManifest();
+        mNativePointer = nativeInitialize(mTab.getWebContents(),
+                mWebappInfo.scopeUri().toString(), mWebappInfo.webManifestUri().toString());
+
+        mTab.addObserver(this);
+        nativeStart(mNativePointer);
+    }
+
+    private void getMetaDataFromAndroidManifest() {
+        if (CommandLine.getInstance().hasSwitch(
+                SWITCH_DO_NOT_USE_META_DATA_FROM_WEBAPK_FOR_TESTING)) {
+            // The metadata are set via {@link setMetadataForTesting()}.
+            return;
+        }
+        try {
+            ApplicationInfo appinfo =
+                    ContextUtils.getApplicationContext().getPackageManager().getApplicationInfo(
+                            mWebappInfo.webApkPackageName(), PackageManager.GET_META_DATA);
+            mStartUrl = appinfo.metaData.getString(META_DATA_START_URL);
+        } catch (PackageManager.NameNotFoundException e) {
+            e.printStackTrace();
+        }
+    }
+
+    /**
+     * Puts the object in a state where it is safe to be destroyed.
+     */
+    public void destroy() {
+        if (mNativePointer != 0) {
+            nativeDestroy(mNativePointer);
+        }
+        mNativePointer = 0;
+    }
+
+    @Override
+    public void onWebContentsSwapped(Tab tab, boolean didStartLoad,
+            boolean didFinishLoad) {
+        updatePointers();
+    }
+
+    @Override
+    public void onContentChanged(Tab tab) {
+        updatePointers();
+    }
+
+    /**
+     * Updates which WebContents the native ManifestUpgradeDetector is monitoring.
+     */
+    private void updatePointers() {
+        nativeReplaceWebContents(mNativePointer, mTab.getWebContents());
+    }
+
+    /**
+     * Called when the updated Web Manifest has been fetched.
+     */
+    @CalledByNative
+    private void onDataAvailable(String startUrl, String scope, String name, String shortName,
+            int displayMode, int orientation, long themeColor, long backgroundColor) {
+        mTab.removeObserver(this);
+        destroy();
+
+        // TODO(hanxi): crbug.com/627824. Validate whether the new WebappInfo is
+        // WebAPK-compatible.
+        final WebappInfo newInfo = WebappInfo.create(mWebappInfo.id(), startUrl,
+                scope, mWebappInfo.encodedIcon(), name, shortName, displayMode, orientation,
+                mWebappInfo.source(), themeColor, backgroundColor, mWebappInfo.isIconGenerated(),
+                mWebappInfo.webApkPackageName(), mWebappInfo.webManifestUri().toString());
+        if (requireUpgrade(newInfo, startUrl)) {
+            upgrade();
+        }
+    }
+
+    /**
+     * Checks whether the WebAPK needs to be upgraded provided the new Web Manifest info.
+     */
+    protected boolean requireUpgrade(WebappInfo newInfo, String startUrl) {
+        boolean scopeMatch = mWebappInfo.scopeUri().equals(newInfo.scopeUri());
+        if (!scopeMatch) {
+            // Sometimes the scope doesn't match due to a missing "/" at the end of the scope URL.
+            // Print log to find such cases.
+            Log.d(TAG, "Needs to request update since the scope from WebappInfo (%s) doesn't match"
+                    + "the one fetched from Web Manifest(%s).", mWebappInfo.scopeUri().toString(),
+                    newInfo.scopeUri().toString());
+            return true;
+        }
+
+        // TODO(hanxi): Add icon comparison.
+        if (!mStartUrl.equals(startUrl)
+                || !mWebappInfo.shortName().equals(newInfo.shortName())

[Yaron, 2016/07/25 15:55:01]

If these can be null (first-glance seems no, but not sure), then use
TextUtils.equals()

[Yaron, 2016/07/25 15:55:02]

we should consider adding a helper method to WebAppInfo but this is specific to
WebApks and not webapp shortcuts. Actually, probably would've been nice to do
this in native if we still had access to the manifest but I see we don't. I'm ok
with his for now. 

[Xi Han, 2016/07/25 20:01:37]

It can't be null, will fallback to "". But I am ok to use TextUtils.equals(),
which looks safer.

[Xi Han, 2016/07/25 20:01:37]

Acknowledged.

+                || !mWebappInfo.name().equals(newInfo.name())
+                || mWebappInfo.backgroundColor() != newInfo.backgroundColor()
+                || mWebappInfo.themeColor() != newInfo.themeColor()
+                || mWebappInfo.orientation() != newInfo.orientation()
+                || mWebappInfo.displayMode() != newInfo.displayMode()) {
+            return true;
+        }
+
+        return false;
+    }
+
+    private void upgrade() {}
+
+    private native long nativeInitialize(WebContents webContents, String scope,
+            String webManifestUrl);
+    private native void nativeReplaceWebContents(long nativeManifestUpgradeDetector,
+            WebContents webContents);
+    private native void nativeDestroy(long nativeManifestUpgradeDetector);
+    private native void nativeStart(long nativeManifestUpgradeDetector);
+}