NopCanvas is only hw accelerated during construction

During construction, we want to make NopCanvas as light as possible so
we just say that we are hw accelerated.
This caused some crashes further down the line for some views that
thought that NopCanvas was hw accelerated. From now on, NopCanvas is
only hw accelerated during construction.

Test: Covered by the existing tests
Change-Id: If09a662312e5c90d011e7ab2cbb524ef7b420d12

tools/layoutlib/bridge/src/com/android/layoutlib/bridge/android/graphics/NopCanvas.java

@@ -31,14 +31,18 @@ import android.graphics.RectF;
  * Canvas implementation that does not do any rendering
  */
 public class NopCanvas extends Canvas {
+    private boolean mIsHardwareAccelerated = true;
+
     public NopCanvas() {
         super();
+        // We return true the first time so there are no allocations for the software renderer in
+        // the constructor
+        mIsHardwareAccelerated = false;
     }
 
     @Override
     public boolean isHardwareAccelerated() {
-        // Return true so there is no allocations for the software renderer in the constructor
-        return true;
+        return mIsHardwareAccelerated;
     }
 
     @Override