Break apart the TabModelBase's JNI calls into its own class

chrome/android/java/src/org/chromium/chrome/browser/tabmodel/TabModelBase.java

Index: chrome/android/java/src/org/chromium/chrome/browser/tabmodel/TabModelBase.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/tabmodel/TabModelBase.java b/chrome/android/java/src/org/chromium/chrome/browser/tabmodel/TabModelBase.java
index 9a144443c3aeefc1974a1fef69d5bb4acb3d5972..275cf1b892ac50b715471a9ae145490536ddf044 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/tabmodel/TabModelBase.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/tabmodel/TabModelBase.java
@@ -35,7 +35,10 @@ public abstract class TabModelBase implements TabModel {
 
     protected final TabModelDelegate mModelDelegate;
 
-    private final ObserverList<TabModelObserver> mObservers;
+    /**
+     * List of Observers monitoring this TabModel.
+     */
+    protected final ObserverList<TabModelObserver> mObservers;
 
     // Undo State Tracking -------------------------------------------------------------------------
 
@@ -53,17 +56,38 @@ public abstract class TabModelBase implements TabModel {
     private int mIndex = INVALID_TAB_INDEX;
 
     /** Native Tab pointer which will be set by nativeInit(). */
-    private long mNativeTabModelImpl = 0;
+    protected long mNativeTabModelImpl = 0;
 
+    /**
+     * Constructs the TabModelBase. If an orderController and modelDelegate are not supplied,
+     * the native side TabModel is not initialized.
+     * @param incognito Whether or not the TabModel is for Incognito mode.
+     * @param orderController Controls the ordering of the Tabs.
+     * @param modelDelegate Delgates calls to the TabModel.
+     */
     public TabModelBase(boolean incognito, TabModelOrderController orderController,
             TabModelDelegate modelDelegate) {
         mIsIncognito = incognito;
-        mNativeTabModelImpl = nativeInit(incognito);
-        mOrderController = orderController;
-        mModelDelegate = modelDelegate;
+
+        if (orderController != null && modelDelegate != null) {
+            initializeNativeTabModel();
+            mOrderController = orderController;
+            mModelDelegate = modelDelegate;
+        } else {
+            mOrderController = null;
+            mModelDelegate = null;
+        }
+
         mObservers = new ObserverList<TabModelObserver>();
     }
 
+    /**
+     * Initialize the native-side TabModelBase.
+     */
+    protected void initializeNativeTabModel() {
+        mNativeTabModelImpl = nativeInit(mIsIncognito);

[David Trainor- moved to gerrit, 2014/10/02 00:00:39]

Even if this works, it might just be because the vtables are aligned properly. 
Are you 100% sure this should work?  We're effectively doing:

reinterpret_cast<TabModelBase*>(reinterpret_cast<intptr>(DocumentTabList*))
which isn't defined to work properly AFAIK...


Look at Tab/ChromeTab to see an example of how to do this safely.

+    }
+
     @Override
     public Profile getProfile() {
         return nativeGetProfileAndroid(mNativeTabModelImpl);
@@ -111,9 +135,10 @@ public abstract class TabModelBase implements TabModel {
 
         for (TabModelObserver obs : mObservers) obs.willAddTab(tab, type);
 
-        boolean selectTab = mOrderController.willOpenInForeground(type, mIsIncognito);
-
-        index = mOrderController.determineInsertionIndex(type, index, tab);
+        boolean selectTab = mOrderController == null
+                ? false : mOrderController.willOpenInForeground(type, mIsIncognito);
+        index = mOrderController == null
+                ? mTabs.size() : mOrderController.determineInsertionIndex(type, index, tab);
         assert index <= mTabs.size();
 
         assert tab.isIncognito() == mIsIncognito;
@@ -631,7 +656,7 @@ public abstract class TabModelBase implements TabModel {
     protected abstract Tab createNewTabForDevTools(String url);
 
     @CalledByNative
-    private boolean isSessionRestoreInProgress() {
+    protected boolean isSessionRestoreInProgress() {
         return mModelDelegate.isSessionRestoreInProgress();
     }