linux: don't paint empty rects.

chrome/browser/renderer_host/backing_store_x.cc

Index: chrome/browser/renderer_host/backing_store_x.cc
diff --git a/chrome/browser/renderer_host/backing_store_x.cc b/chrome/browser/renderer_host/backing_store_x.cc
index a4b53c36dcd3c67052a2abb6a6fb0c93c849cee5..dc1beafd3a6124a5586615a2fd1e783a20a68a1b 100644
--- a/chrome/browser/renderer_host/backing_store_x.cc
+++ b/chrome/browser/renderer_host/backing_store_x.cc
@@ -156,6 +156,9 @@ void BackingStore::PaintRect(base::ProcessHandle process,
   if (!display_)
     return;
 
+  if (bitmap_rect.IsEmpty())
+    return;
+
   if (!use_render_)
     return PaintRectWithoutXrender(bitmap, bitmap_rect);