Remove some more OS_CHROMEOS from browser.

ash/test/test_shell_delegate.cc

Index: ash/test/test_shell_delegate.cc
===================================================================
--- ash/test/test_shell_delegate.cc	(revision 137127)
+++ ash/test/test_shell_delegate.cc	(working copy)
@@ -60,6 +60,9 @@
 void TestShellDelegate::OpenMobileSetup() {
 }
 
+void TestShellDelegate::ShowKeyboardOverlay(ui::AcceleratorTarget* target) {
+}
+
 content::BrowserContext* TestShellDelegate::GetCurrentBrowserContext() {
   return new TestBrowserContext();
 }