Allow "freezing" NativePages to spare up memory.

chrome/android/java/src/org/chromium/chrome/browser/FrozenNativePage.java

Index: chrome/android/java/src/org/chromium/chrome/browser/FrozenNativePage.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/FrozenNativePage.java b/chrome/android/java/src/org/chromium/chrome/browser/FrozenNativePage.java
new file mode 100644
index 0000000000000000000000000000000000000000..201718e4e1b6e74a1713bc7ff267e842548b678c
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/FrozenNativePage.java
@@ -0,0 +1,71 @@
+// Copyright 2014 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;
+
+import android.view.View;
+
+/**
+ * A empty stand-in for a native page. An inactive NativePage may be replaced with a
+ * FrozenNativePage to free up resources.
+ *
+ * Any method may be called on this object, except for getView(), which will trigger an assert and
+ * return null.
+ */
+public class FrozenNativePage implements NativePage {
+    private final String mUrl;
+    private final String mHost;
+    private final String mTitle;
+    private final int mBackgroundColor;
+
+    /**
+     * Creates a FrozenNativePage to replace the given NativePage and destroys the NativePage.
+     */
+    public static FrozenNativePage freeze(NativePage nativePage) {
+        FrozenNativePage fnp = new FrozenNativePage(nativePage);
+        nativePage.destroy();
+        return fnp;
+    }
+
+    private FrozenNativePage(NativePage nativePage) {
+        mHost = nativePage.getHost();
+        mUrl = nativePage.getUrl();
+        mTitle = nativePage.getTitle();
+        mBackgroundColor = nativePage.getBackgroundColor();
+    }
+
+    @Override
+    public View getView() {
+        assert false;
+        return null;
+    }
+
+    @Override
+    public String getTitle() {
+        return mTitle;
+    }
+
+    @Override
+    public String getUrl() {
+        return mUrl;
+    }
+
+    @Override
+    public String getHost() {
+        return mHost;
+    }
+
+    @Override
+    public int getBackgroundColor() {
+        return mBackgroundColor;
+    }
+
+    @Override
+    public void updateForUrl(String url) {
+    }
+
+    @Override
+    public void destroy() {
+    }
+}