Java versions of BlimpContents[,Observer] and BlimpNavigationController

blimp/client/core/android/java/src/org/chromium/blimp/core/BlimpContentsObserverProxy.java

Index: blimp/client/core/android/java/src/org/chromium/blimp/core/BlimpContentsObserverProxy.java
diff --git a/blimp/client/core/android/java/src/org/chromium/blimp/core/BlimpContentsObserverProxy.java b/blimp/client/core/android/java/src/org/chromium/blimp/core/BlimpContentsObserverProxy.java
new file mode 100644
index 0000000000000000000000000000000000000000..657c7bb852cd7ed35c548dc4512827d650607b75
--- /dev/null
+++ b/blimp/client/core/android/java/src/org/chromium/blimp/core/BlimpContentsObserverProxy.java
@@ -0,0 +1,53 @@
+// 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.blimp.core;
+
+import org.chromium.base.ObserverList;
+import org.chromium.base.annotations.CalledByNative;
+import org.chromium.base.annotations.JNINamespace;
+import org.chromium.blimp.core_public.BlimpContentsObserver;
+
+/**
+ * Serves as a compound observer proxy for dispatching BlimpContentsObserver callbacks,
+ * avoiding redundant JNI-related work when there are multiple Java-based observers.
+ */
+@JNINamespace("blimp::client")
+class BlimpContentsObserverProxy implements BlimpContentsObserver {
+    private final ObserverList<BlimpContentsObserver> mObservers = new ObserverList<>();
+
+    private long mNativeBlimpContentsObserverProxy;
+
+    BlimpContentsObserverProxy(BlimpContentsImpl blimpContentsImpl) {
+        mNativeBlimpContentsObserverProxy = nativeInit(blimpContentsImpl);
+    }
+
+    void destroy() {
+        if (mNativeBlimpContentsObserverProxy != 0) {
+            nativeDestroy(mNativeBlimpContentsObserverProxy);
+            mNativeBlimpContentsObserverProxy = 0;
+        }
+        mObservers.clear();
+    }
+
+    void addObserver(BlimpContentsObserver observer) {
+        assert mNativeBlimpContentsObserverProxy != 0;
+        mObservers.addObserver(observer);
+    }
+
+    void removeObserver(BlimpContentsObserver observer) {
+        mObservers.removeObserver(observer);
+    }
+
+    @Override
+    @CalledByNative
+    public void onUrlUpdated(String url) {
+        for (BlimpContentsObserver observer : mObservers) {
+            observer.onUrlUpdated(url);
+        }
+    }
+
+    private native long nativeInit(BlimpContentsImpl blimpContentsImpl);
+    private native void nativeDestroy(long nativeBlimpContentsObserverProxy);
+}