Make it possible to have 1 PpapiGlobals per thread. Update unit tests.

ppapi/shared_impl/proxy_lock.h

Index: ppapi/shared_impl/proxy_lock.h
diff --git a/ppapi/shared_impl/proxy_lock.h b/ppapi/shared_impl/proxy_lock.h
index cc90501d9400d17f362c221a0d6e5382253443e0..6570f5a718c01158a076bedc581324ca8d488d94 100644
--- a/ppapi/shared_impl/proxy_lock.h
+++ b/ppapi/shared_impl/proxy_lock.h
@@ -34,14 +34,6 @@ class PPAPI_SHARED_EXPORT ProxyLock {
   // Relinquish the proxy lock. If the lock has not been set, this does nothing.
   static void Release();
 
-  // Set the lock that ProxyLock will use. The caller is responsible for
-  // ensuring that the lock stays valid so long as the ProxyLock may be in use.
-  static void Set(base::Lock* lock);
-  // Set the lock to NULL.
-  static void Reset();
- private:
-  static base::Lock* lock_;
-
   DISALLOW_IMPLICIT_CONSTRUCTORS(ProxyLock);
 };