Make AndroidView an interface

Summary:
The current AndroidView stipulates that the backing shadow node can't
be a FlatShadowNode. In some cases, however, we want to apply some of the same
logic (ex not adding NodeRegions, etc) to other ViewManagers that have a
FlatShadowNode backing (and that don't necessarily create a FlatViewGroup).
This commit renames AndroidView to NativeViewWrapper, and re-introduces
AndroidView as an interface, so that logic for padding, NodeRegions, etc can
be shared.

Differential Revision: D2942387

ReactAndroid/src/main/java/com/facebook/react/flat/NativeViewWrapper.java

@@ -0,0 +1,97 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+package com.facebook.react.flat;
+
+import javax.annotation.Nullable;
+
+import com.facebook.csslayout.CSSNode;
+import com.facebook.react.uimanager.ReactStylesDiffMap;
+import com.facebook.react.uimanager.ReactShadowNode;
+import com.facebook.react.uimanager.ThemedReactContext;
+import com.facebook.react.uimanager.ViewGroupManager;
+import com.facebook.react.uimanager.ViewManager;
+
+/* package */ final class NativeViewWrapper extends FlatShadowNode implements AndroidView {
+
+  @Nullable private final ReactShadowNode mReactShadowNode;
+  private final boolean mNeedsCustomLayoutForChildren;
+  private boolean mPaddingChanged = false;
+
+  /* package */ NativeViewWrapper(ViewManager viewManager) {
+    ReactShadowNode reactShadowNode = viewManager.createShadowNodeInstance();
+    if (reactShadowNode instanceof CSSNode.MeasureFunction) {
+      mReactShadowNode = reactShadowNode;
+      setMeasureFunction((CSSNode.MeasureFunction) reactShadowNode);
+    } else {
+      mReactShadowNode = null;
+    }
+
+    if (viewManager instanceof ViewGroupManager) {
+      ViewGroupManager viewGroupManager = (ViewGroupManager) viewManager;
+      mNeedsCustomLayoutForChildren = viewGroupManager.needsCustomLayoutForChildren();
+    } else {
+      mNeedsCustomLayoutForChildren = false;
+    }
+
+    forceMountToView();
+  }
+
+  @Override
+  public boolean needsCustomLayoutForChildren() {
+    return mNeedsCustomLayoutForChildren;
+  }
+
+  @Override
+  public boolean isPaddingChanged() {
+    return mPaddingChanged;
+  }
+
+  @Override
+  public void resetPaddingChanged() {
+    mPaddingChanged = false;
+  }
+
+  @Override
+  public void setBackgroundColor(int backgroundColor) {
+    // suppress, this is handled by a ViewManager
+  }
+
+  @Override
+  public void setThemedContext(ThemedReactContext themedContext) {
+    super.setThemedContext(themedContext);
+
+    if (mReactShadowNode != null) {
+      mReactShadowNode.setThemedContext(themedContext);
+    }
+  }
+
+  @Override
+  /* package*/ void handleUpdateProperties(ReactStylesDiffMap styles) {
+    if (mReactShadowNode != null) {
+      mReactShadowNode.updateProperties(styles);
+    }
+  }
+
+  @Override
+  public void addChildAt(CSSNode child, int i) {
+    super.addChildAt(child, i);
+    if (child instanceof FlatShadowNode) {
+      ((FlatShadowNode) child).forceMountToView();
+    }
+  }
+
+  @Override
+  public void setPadding(int spacingType, float padding) {
+    if (getPadding().set(spacingType, padding)) {
+      mPaddingChanged = true;
+      dirty();
+    }
+  }
+}