cros: Remove some OS platform ifdefs from ash

ash/content/shell_content_state.cc

Index: ash/content/shell_content_state.cc
diff --git a/ash/content/shell_content_state.cc b/ash/content/shell_content_state.cc
index 990c27c0d524e3617f3a4a87ac2e9d1bfb2aadc0..f9abb727609c36db9e8a04e46fd75e6ecaf9acd5 100644
--- a/ash/content/shell_content_state.cc
+++ b/ash/content/shell_content_state.cc
@@ -32,12 +32,11 @@ void ShellContentState::DestroyInstance() {
 }
 
 ShellContentState::ShellContentState() {
-// The keyboard system must be initialized before the RootWindowController is
-// created.
-#if defined(OS_CHROMEOS)
+  // The keyboard system must be initialized before the RootWindowController is
+  // created.
   keyboard::InitializeKeyboard();
-#endif
 }
+
 ShellContentState::~ShellContentState() {}
 
 }  // namespace ash