Fix a FORWARD_NULL defect reported by Coverity....

views/controls/scroll_view.cc

Index: views/controls/scroll_view.cc
===================================================================
--- views/controls/scroll_view.cc	(revision 21299)
+++ views/controls/scroll_view.cc	(working copy)
@@ -261,9 +261,9 @@
     return gfx::Rect();
 
   const int x =
-      (horiz_sb_ && horiz_sb_->IsVisible()) ? horiz_sb_->GetPosition() : 0;
+      horiz_sb_->IsVisible() ? horiz_sb_->GetPosition() : 0;
   const int y =
-      (vert_sb_ && vert_sb_->IsVisible()) ? vert_sb_->GetPosition() : 0;
+      vert_sb_->IsVisible() ? vert_sb_->GetPosition() : 0;
   return gfx::Rect(x, y, viewport_->width(), viewport_->height());
 }
 
@@ -271,10 +271,8 @@
                                                  int y,
                                                  int width,
                                                  int height) {
-  if (!contents_ || ((!horiz_sb_ || !horiz_sb_->IsVisible()) &&
-                     (!vert_sb_ || !vert_sb_->IsVisible()))) {
+  if (!contents_ || (!horiz_sb_->IsVisible() && !vert_sb_->IsVisible()))
     return;
-  }
 
   // Figure out the maximums for this scroll view.
   const int contents_max_x =
@@ -337,7 +335,7 @@
   }
 }
 
-// TODO(ACW). We should really use ScrollWindowEx as needed
+// TODO(ACW): We should really use ScrollWindowEx as needed
 void ScrollView::ScrollToPosition(ScrollBar* source, int position) {
   if (!contents_)
     return;
@@ -502,7 +500,7 @@
     : VariableRowHeightScrollHelper(NULL),
       top_margin_(top_margin),
       row_height_(row_height) {
-  DCHECK(row_height > 0);
+  DCHECK_GT(row_height, 0);
 }
 
 VariableRowHeightScrollHelper::RowInfo