Split fetcher logic out of ManifestUpgradeDetector

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

Index: chrome/android/java/src/org/chromium/chrome/browser/webapps/ManifestUpgradeDetectorFetcher.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/webapps/ManifestUpgradeDetectorFetcher.java b/chrome/android/java/src/org/chromium/chrome/browser/webapps/ManifestUpgradeDetectorFetcher.java
new file mode 100644
index 0000000000000000000000000000000000000000..4c1e5c119634f9ef5cb1fbe4465dc03f0120f5d9
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/webapps/ManifestUpgradeDetectorFetcher.java
@@ -0,0 +1,96 @@
+// 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.annotations.CalledByNative;
+import org.chromium.chrome.browser.tab.EmptyTabObserver;
+import org.chromium.chrome.browser.tab.Tab;
+import org.chromium.content_public.browser.WebContents;
+
+/**
+ * Downloads the Web Manifest if the web site still uses the {@link manifestUrl} passed to the
+ * constructor.
+ */
+public class ManifestUpgradeDetectorFetcher extends EmptyTabObserver {
+
+    /**
+     * Called once the Web Manifest has been downloaded.
+     */
+    public interface Callback {
+        public void onGotManifestData(String startUrl, String scopeUrl, String name,
+                String shortName, int displayMode, int orientation, long themeColor,
+                long backgroundColor);
+    }
+
+    /**
+     * Pointer to the native side ManifestUpgradeDetectorFetcher. The Java side owns the native side
+     * ManifestUpgradeDetectorFetcher.
+     */
+    private long mNativePointer;
+
+    /** The tab that is being observed. */
+    private final Tab mTab;
+
+    private Callback mCallback;
+
+    public ManifestUpgradeDetectorFetcher(Tab tab, String scopeUrl, String manifestUrl) {
+        mTab = tab;
+        mNativePointer = nativeInitialize(scopeUrl, manifestUrl);
+    }
+
+    /**
+     * Starts fetching the web manifest resources.
+     * @param callback Called once the Web Manifest has been downloaded.
+     */
+    public void start(Callback callback) {
+        mCallback = callback;
+        mTab.addObserver(this);
+        nativeStart(mNativePointer, mTab.getWebContents());
+    }
+
+    /**
+     * Puts the object in a state where it is safe to be destroyed.
+     */
+    public void destroy() {
+        mTab.removeObserver(this);
+        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 ManifestUpgradeDetectorFetcher 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 scopeUrl, String name, String shortName,
+            int displayMode, int orientation, long themeColor, long backgroundColor) {
+        mCallback.onGotManifestData(startUrl, scopeUrl, name, shortName, displayMode, orientation,
+                themeColor, backgroundColor);
+    }
+
+    private native long nativeInitialize(String scope, String webManifestUrl);
+    private native void nativeReplaceWebContents(
+            long nativeManifestUpgradeDetectorFetcher, WebContents webContents);
+    private native void nativeDestroy(long nativeManifestUpgradeDetectorFetcher);
+    private native void nativeStart(
+            long nativeManifestUpgradeDetectorFetcher, WebContents webContents);
+}