[Android] Add proxy for Java-based WebContentsObservers

content/public/android/java/src/org/chromium/content/browser/webcontents/WebContentsObserverProxy.java

Index: content/public/android/java/src/org/chromium/content/browser/webcontents/WebContentsObserverProxy.java
diff --git a/content/public/android/java/src/org/chromium/content/browser/webcontents/WebContentsObserverProxy.java b/content/public/android/java/src/org/chromium/content/browser/webcontents/WebContentsObserverProxy.java
new file mode 100644
index 0000000000000000000000000000000000000000..fdae8f3a3afe3a0c9de2649107d28757a127c843
--- /dev/null
+++ b/content/public/android/java/src/org/chromium/content/browser/webcontents/WebContentsObserverProxy.java
@@ -0,0 +1,236 @@
+// 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.content.browser.webcontents;
+
+import org.chromium.base.CalledByNative;
+import org.chromium.base.JNINamespace;
+import org.chromium.base.ObserverList;
+import org.chromium.base.ObserverList.RewindableIterator;
+import org.chromium.base.ThreadUtils;
+import org.chromium.content_public.browser.WebContentsObserver;
+
+/**
+ * Serves as a compound observer proxy for dispatching WebContentsObserver callbacks,
+ * avoiding redundant JNI-related work when there are multiple Java-based observers.
+ */
+@JNINamespace("content")
+class WebContentsObserverProxy extends WebContentsObserver {
+    private long mNativeWebContentsObserverProxy;
+    private final ObserverList<WebContentsObserver> mObservers;
+    private final RewindableIterator<WebContentsObserver> mObserversIterator;
+
+    /**
+     * Constructs a new WebContentsObserverProxy for a given WebContents
+     * instance. A native WebContentsObserver instance will be created, which
+     * will observe the native counterpart to the provided WebContents.
+     *
+     * @param webContents The WebContents instance to observe.
+     */
+    public WebContentsObserverProxy(WebContentsImpl webContents) {
+        ThreadUtils.assertOnUiThread();
+        mNativeWebContentsObserverProxy = nativeInit(webContents);
+        mObservers = new ObserverList<WebContentsObserver>();
+        mObserversIterator = mObservers.rewindableIterator();
+    }
+
+    /**
+     * Add an observer to the list of proxied observers.
+     * @param observer The WebContentsObserver instance to add.
+     */
+    void addObserver(WebContentsObserver observer) {
+        assert mNativeWebContentsObserverProxy != 0;
+        mObservers.addObserver(observer);
+    }
+
+    /**
+     * Remove an observer from the list of proxied observers.
+     * @param observer The WebContentsObserver instance to remove.
+     */
+    void removeObserver(WebContentsObserver observer) {
+        mObservers.removeObserver(observer);
+    }
+
+    /**
+     * @return Whether there are any active, proxied observers.
+     */
+    boolean hasObservers() {
+        return !mObservers.isEmpty();
+    }
+
+    @Override
+    @CalledByNative
+    public void renderViewReady() {
+        for (mObserversIterator.rewind(); mObserversIterator.hasNext();) {
+            mObserversIterator.next().renderViewReady();
+        }
+    }
+
+    @Override
+    @CalledByNative
+    public void renderProcessGone(boolean wasOomProtected) {
+        for (mObserversIterator.rewind(); mObserversIterator.hasNext();) {
+            mObserversIterator.next().renderProcessGone(wasOomProtected);
+        }
+    }
+
+    @Override
+    @CalledByNative
+    public void didStartLoading(String url) {
+        for (mObserversIterator.rewind(); mObserversIterator.hasNext();) {
+            mObserversIterator.next().didStartLoading(url);
+        }
+    }
+
+    @Override
+    @CalledByNative
+    public void didStopLoading(String url) {
+        for (mObserversIterator.rewind(); mObserversIterator.hasNext();) {
+            mObserversIterator.next().didStopLoading(url);
+        }
+    }
+
+    @Override
+    @CalledByNative
+    public void didFailLoad(boolean isProvisionalLoad, boolean isMainFrame, int errorCode,
+            String description, String failingUrl) {
+        for (mObserversIterator.rewind(); mObserversIterator.hasNext();) {
+            mObserversIterator.next().didFailLoad(
+                    isProvisionalLoad, isMainFrame, errorCode, description, failingUrl);
+        }
+    }
+
+    @Override
+    public void didNavigateMainFrame(String url, String baseUrl,
+            boolean isNavigationToDifferentPage, boolean isFragmentNavigation) {
+        for (mObserversIterator.rewind(); mObserversIterator.hasNext();) {
+            mObserversIterator.next().didNavigateMainFrame(
+                    url, baseUrl, isNavigationToDifferentPage, isFragmentNavigation);
+        }
+    }
+
+    @Override
+    @CalledByNative
+    public void didNavigateMainFrame(String url, String baseUrl,
+            boolean isNavigationToDifferentPage, boolean isFragmentNavigation, int statusCode) {
+        didNavigateMainFrame(url, baseUrl, isNavigationToDifferentPage, isFragmentNavigation);
+    }
+
+    @Override
+    @CalledByNative
+    public void didFirstVisuallyNonEmptyPaint() {
+        for (mObserversIterator.rewind(); mObserversIterator.hasNext();) {
+            mObserversIterator.next().didFirstVisuallyNonEmptyPaint();
+        }
+    }
+
+    @Override
+    @CalledByNative
+    public void didNavigateAnyFrame(String url, String baseUrl, boolean isReload) {
+        for (mObserversIterator.rewind(); mObserversIterator.hasNext();) {
+            mObserversIterator.next().didNavigateAnyFrame(url, baseUrl, isReload);
+        }
+    }
+
+    @Override
+    @CalledByNative
+    public void documentAvailableInMainFrame() {
+        for (mObserversIterator.rewind(); mObserversIterator.hasNext();) {
+            mObserversIterator.next().documentAvailableInMainFrame();
+        }
+    }
+
+    @Override
+    @CalledByNative
+    public void didStartProvisionalLoadForFrame(long frameId, long parentFrameId,
+            boolean isMainFrame, String validatedUrl, boolean isErrorPage, boolean isIframeSrcdoc) {
+        for (mObserversIterator.rewind(); mObserversIterator.hasNext();) {
+            mObserversIterator.next().didStartProvisionalLoadForFrame(
+                    frameId, parentFrameId, isMainFrame, validatedUrl, isErrorPage, isIframeSrcdoc);
+        }
+    }
+
+    @Override
+    @CalledByNative
+    public void didCommitProvisionalLoadForFrame(
+            long frameId, boolean isMainFrame, String url, int transitionType) {
+        for (mObserversIterator.rewind(); mObserversIterator.hasNext();) {
+            mObserversIterator.next().didCommitProvisionalLoadForFrame(
+                    frameId, isMainFrame, url, transitionType);
+        }
+    }
+
+    @Override
+    @CalledByNative
+    public void didFinishLoad(long frameId, String validatedUrl, boolean isMainFrame) {
+        for (mObserversIterator.rewind(); mObserversIterator.hasNext();) {
+            mObserversIterator.next().didFinishLoad(frameId, validatedUrl, isMainFrame);
+        }
+    }
+
+    @Override
+    @CalledByNative
+    public void documentLoadedInFrame(long frameId) {
+        for (mObserversIterator.rewind(); mObserversIterator.hasNext();) {
+            mObserversIterator.next().documentLoadedInFrame(frameId);
+        }
+    }
+
+    @Override
+    @CalledByNative
+    public void navigationEntryCommitted() {
+        for (mObserversIterator.rewind(); mObserversIterator.hasNext();) {
+            mObserversIterator.next().navigationEntryCommitted();
+        }
+    }
+
+    @Override
+    @CalledByNative
+    public void didAttachInterstitialPage() {
+        for (mObserversIterator.rewind(); mObserversIterator.hasNext();) {
+            mObserversIterator.next().didAttachInterstitialPage();
+        }
+    }
+
+    @Override
+    @CalledByNative
+    public void didDetachInterstitialPage() {
+        for (mObserversIterator.rewind(); mObserversIterator.hasNext();) {
+            mObserversIterator.next().didDetachInterstitialPage();
+        }
+    }
+
+    @Override
+    @CalledByNative
+    public void didChangeThemeColor(int color) {
+        for (mObserversIterator.rewind(); mObserversIterator.hasNext();) {
+            mObserversIterator.next().didChangeThemeColor(color);
+        }
+    }
+
+    @Override
+    @CalledByNative
+    public void didStartNavigationToPendingEntry(String url) {
+        for (mObserversIterator.rewind(); mObserversIterator.hasNext();) {
+            mObserversIterator.next().didStartNavigationToPendingEntry(url);
+        }
+    }
+
+    @Override
+    @CalledByNative
+    public void destroy() {
+        // Super destruction semantics (removing the observer from the
+        // Java-based WebContents) are quite different, so we explicitly avoid
+        // calling it here.
+        ThreadUtils.assertOnUiThread();
+        mObservers.clear();
+        if (mNativeWebContentsObserverProxy != 0) {
+            nativeDestroy(mNativeWebContentsObserverProxy);
+            mNativeWebContentsObserverProxy = 0;
+        }
+    }
+
+    private native long nativeInit(WebContentsImpl webContents);
+    private native void nativeDestroy(long nativeWebContentsObserverProxy);
+}