linux: don't paint empty rects.

chrome/browser/renderer_host/backing_store_x.cc

 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/renderer_host/backing_store.h"
 
 #include <stdlib.h>
 #include <utility>
 
 #include "base/compiler_specific.h"
@@ skipping 138 matching lines @@
 
   XFreePixmap(display_, pixmap);
 }
 
 void BackingStore::PaintRect(base::ProcessHandle process,
                              TransportDIB* bitmap,
                              const gfx::Rect& bitmap_rect) {
   if (!display_)
     return;
 
+  if (bitmap_rect.IsEmpty())
+    return;
+
   if (!use_render_)
     return PaintRectWithoutXrender(bitmap, bitmap_rect);
 
   const int width = bitmap_rect.width();
   const int height = bitmap_rect.height();
   Picture picture;
   Pixmap pixmap;
 
   if (use_shared_memory_) {
     const XID shmseg = bitmap->MapToX(display_);
@@ skipping 94 matching lines @@
   }
 
   PaintRect(process, bitmap, bitmap_rect);
 }
 
 void BackingStore::ShowRect(const gfx::Rect& rect, XID target) {
   XCopyArea(display_, pixmap_, target, static_cast<GC>(pixmap_gc_),
             rect.x(), rect.y(), rect.width(), rect.height(),
             rect.x(), rect.y());
 }