Remove using directives ("using namespace x") from ppapi/, take 2.

Testing to see if this route avoids breaking the Linux Deterministic bot.

TBR=bbudge

Bug: 82078
Change-Id: I1512141cc886dafa6683f5ff38c6a50f35be067a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1818998Reviewed-by: Peter Kasting <pkasting@chromium.org>
Commit-Queue: Peter Kasting <pkasting@chromium.org>
Cr-Commit-Position: refs/heads/master@{#698817}

ppapi/cpp/private/var_private.cc

@@ -24,7 +24,7 @@ template <> const char* interface_name<PPB_Var_Deprecated>() {
 
 }  // namespace
 
-using namespace deprecated;
+using deprecated::ScriptableObject;
 
 VarPrivate::VarPrivate(const InstanceHandle& instance,
                        ScriptableObject* object) {