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

webkit/plugins/ppapi/host_globals.h

Index: webkit/plugins/ppapi/host_globals.h
diff --git a/webkit/plugins/ppapi/host_globals.h b/webkit/plugins/ppapi/host_globals.h
index db840aa85ed3c618935cf1e2ed71f063f525e027..57dde570870eb08309ac94cd9eaacc5620749aea 100644
--- a/webkit/plugins/ppapi/host_globals.h
+++ b/webkit/plugins/ppapi/host_globals.h
@@ -22,12 +22,17 @@ class PluginModule;
 class HostGlobals : public ::ppapi::PpapiGlobals {
  public:
   HostGlobals();
+  HostGlobals(::ppapi::PpapiGlobals::ForTest);
   virtual ~HostGlobals();
 
   // Getter for the global singleton. Generally, you should use
   // PpapiGlobals::Get() when possible. Use this only when you need some
   // host-specific functionality.
-  inline static HostGlobals* Get() { return host_globals_; }
+  inline static HostGlobals* Get() {
+    if (host_globals_)
+      return host_globals_;
+    return static_cast<HostGlobals*>(PpapiGlobals::Get());
+  }
 
   // PpapiGlobals implementation.
   virtual ::ppapi::ResourceTracker* GetResourceTracker() OVERRIDE;