Revert of PPAPI: Fix GetBrowserInterface race conditions

ppapi/proxy/plugin_globals.cc

Index: ppapi/proxy/plugin_globals.cc
diff --git a/ppapi/proxy/plugin_globals.cc b/ppapi/proxy/plugin_globals.cc
index b372207c6f00e124ffbc250eebec3ba34b6f89ff..82e16ffe328582f2a5bade188fad7057d1e4e4be 100644
--- a/ppapi/proxy/plugin_globals.cc
+++ b/ppapi/proxy/plugin_globals.cc
@@ -192,8 +192,11 @@
 }
 
 IPC::Sender* PluginGlobals::GetBrowserSender() {
-  // CAUTION: This function is called without the ProxyLock. See also
-  // InterfaceList::GetInterfaceForPPB.
+  if (!browser_sender_.get()) {
+    browser_sender_.reset(
+        new BrowserSender(plugin_proxy_delegate_->GetBrowserSender()));
+  }
+
   return browser_sender_.get();
 }
 
@@ -214,12 +217,6 @@
       connection, instance, desc, prefs);
 }
 
-void PluginGlobals::SetPluginProxyDelegate(PluginProxyDelegate* delegate) {
-  plugin_proxy_delegate_ = delegate;
-  browser_sender_.reset(
-      new BrowserSender(plugin_proxy_delegate_->GetBrowserSender()));
-}
-
 MessageLoopResource* PluginGlobals::loop_for_main_thread() {
   return loop_for_main_thread_.get();
 }