Disable OmniboxViewTest.Escape for all AURA since it is also broken for Linux dbg bulids.

The test must be faulty, as I was able to confirm the browser exhibits
the correct behavior in the same checkout/build on my desktop.

BUG=158913
TBR=pkasting@chromium.org

Review URL: https://codereview.chromium.org/645023004

Cr-Commit-Position: refs/heads/master@{#300160}

chrome/browser/ui/omnibox/omnibox_view_browsertest.cc

@@ -539,7 +539,7 @@ IN_PROC_BROWSER_TEST_F(OmniboxViewTest, MAYBE_BackspaceInKeywordMode) {
 }
 
 // http://crbug.com/158913
-#if defined(OS_CHROMEOS) || defined(OS_WIN)
+#if defined(USE_AURA)
 #define MAYBE_Escape DISABLED_Escape
 #else
 #define MAYBE_Escape Escape