Implement GetSandboxType() on all platforms and implement for all process types.

content/common/sandbox_win.h

Index: content/common/sandbox_win.h
diff --git a/content/common/sandbox_win.h b/content/common/sandbox_win.h
index 7fe52a85aaa4b6df40e94f3794bf5252ee8b0a3f..7998f154d01b6bbbd3e72bde463c526653318407 100644
--- a/content/common/sandbox_win.h
+++ b/content/common/sandbox_win.h
@@ -30,6 +30,10 @@ void SetJobLevel(const base::CommandLine& cmd_line,
 // Closes handles that are opened at process creation and initialization.
 void AddBaseHandleClosePolicy(sandbox::TargetPolicy* policy);
 
+// Add App container policy on supported OS.
+void MaybeAddAppContainerPolicy(sandbox::TargetPolicy* policy,
+                                const wchar_t* sid);
+
 bool InitBrokerServices(sandbox::BrokerServices* broker_services);
 
 bool InitTargetServices(sandbox::TargetServices* target_services);