PPAPI: Add unlocking for PPP calls and callbacks. Add more locking.

ppapi/proxy/ppb_core_proxy.cc

Index: ppapi/proxy/ppb_core_proxy.cc
diff --git a/ppapi/proxy/ppb_core_proxy.cc b/ppapi/proxy/ppb_core_proxy.cc
index 842ed860649c940548d0c0eceacb09005fb8b8a6..bd16c669a8ff0837f5f0b797769516d8c6651463 100644
--- a/ppapi/proxy/ppb_core_proxy.cc
+++ b/ppapi/proxy/ppb_core_proxy.cc
@@ -55,7 +55,7 @@ void CallbackWrapper(PP_CompletionCallback callback, int32_t result) {
   TRACE_EVENT2("ppapi proxy", "CallOnMainThread callback",
                "Func", reinterpret_cast<void*>(callback.func),
                "UserData", callback.user_data);
-  PP_RunCompletionCallback(&callback, result);
+  CallWhileUnlocked(PP_RunCompletionCallback, &callback, result);
 }
 
 void CallOnMainThread(int delay_in_ms,
@@ -63,7 +63,7 @@ void CallOnMainThread(int delay_in_ms,
                       int32_t result) {
   GetMainThreadMessageLoop()->PostDelayedTask(
       FROM_HERE,
-      base::Bind(&CallbackWrapper, callback, result),
+      RunWhileLocked(base::Bind(&CallbackWrapper, callback, result)),
       delay_in_ms);
 }