Fix for a coverity reported error

views/controls/button/image_button.cc

Index: views/controls/button/image_button.cc
===================================================================
--- views/controls/button/image_button.cc	(revision 21433)
+++ views/controls/button/image_button.cc	(working copy)
@@ -18,7 +18,6 @@
 
 ImageButton::ImageButton(ButtonListener* listener)
     : CustomButton(listener),
-      background_image_(NULL),
       h_alignment_(ALIGN_LEFT),
       v_alignment_(ALIGN_TOP) {
   // By default, we request that the gfx::Canvas passed to our View::Paint()
@@ -37,11 +36,14 @@
 void ImageButton::SetBackground(SkColor color,
                                 SkBitmap* image,
                                 SkBitmap* mask) {
-  if (!color && !image)
-    background_image_.reset(NULL);
+  if (!image || !mask) {
+    background_image_.reset();
+    return;
+  }
 
-  background_image_.reset(new SkBitmap(
-      skia::ImageOperations::CreateButtonBackground(color, *image, *mask)));
+  background_image_ = skia::ImageOperations::CreateButtonBackground(color,
+                                                                    *image,
+                                                                    *mask);
 }
 
 void ImageButton::SetImageAlignment(HorizontalAlignment h_align,
@@ -79,8 +81,8 @@
     else if (v_alignment_ == ALIGN_BOTTOM)
       y = height() - img.height();
 
-    if (background_image_.get())
-      canvas->DrawBitmapInt(*(background_image_.get()), x, y);
+    if (!background_image_.empty())
+      canvas->DrawBitmapInt(background_image_, x, y);
     canvas->DrawBitmapInt(img, x, y);
   }
   PaintFocusBorder(canvas);