Widget preview improvements

- Make widget preview bitmaps as small as they can be, saving ~0.7-2MB peak memory (5104303)
- When adding/dragging a widget, make the drag outline/drag view much more closely match the actual size (5566938)

Change-Id: I5b5b7b84fa551d56432a76223b1a9e4de620ff56

src/com/android/launcher2/PagedViewGridLayout.java

@@ -30,6 +30,7 @@ public class PagedViewGridLayout extends GridLayout implements Page {
 
     private int mCellCountX;
     private int mCellCountY;
+    private Runnable mOnLayoutListener;
 
     public PagedViewGridLayout(Context context, int cellCountX, int cellCountY) {
         super(context, null, 0);
@@ -57,6 +58,17 @@ public class PagedViewGridLayout extends GridLayout implements Page {
                 heightMeasureSpec);
     }
 
+    public void setOnLayoutListener(Runnable r) {
+        mOnLayoutListener = r;
+    }
+
+    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
+        super.onLayout(changed, left, top, right, bottom);
+        if (mOnLayoutListener != null) {
+            mOnLayoutListener.run();
+        }
+    }
+
     @Override
     public boolean onTouchEvent(MotionEvent event) {
         boolean result = super.onTouchEvent(event);