Revert 106717 - Revert 106677 (caused several PPAPI test timeouts, see http://crbug.com/101154)

ppapi/proxy/enter_proxy.h

Index: ppapi/proxy/enter_proxy.h
===================================================================
--- ppapi/proxy/enter_proxy.h	(revision 106763)
+++ ppapi/proxy/enter_proxy.h	(working copy)
@@ -166,6 +166,82 @@
   pp::CompletionCallback callback_;
 };
 
+// Like EnterHostFromHostResourceForceCallback but for Function APIs. It takes
+// an instance instead of a resource ID.
+template<typename FunctionT>
+class EnterHostFunctionForceCallback
+    : public thunk::EnterFunctionNoLock<FunctionT> {
+ public:
+  // For callbacks that take no parameters except the "int32_t result". Most
+  // implementations will use the 1-extra-argument constructor below.
+  template<class CallbackFactory, typename Method>
+  EnterHostFunctionForceCallback(PP_Instance instance,
+                                 CallbackFactory& factory,
+                                 Method method)
+      : thunk::EnterFunctionNoLock<FunctionT>(instance, false),
+        needs_running_(true),
+        callback_(factory.NewOptionalCallback(method)) {
+    if (this->failed())
+      RunCallback(PP_ERROR_BADARGUMENT);
+  }
+
+  // For callbacks that take an extra parameter as a closure.
+  template<class CallbackFactory, typename Method, typename A>
+  EnterHostFunctionForceCallback(PP_Instance instance,
+                                 CallbackFactory& factory,
+                                 Method method,
+                                 const A& a)
+      : thunk::EnterFunctionNoLock<FunctionT>(instance, false),
+        needs_running_(true),
+        callback_(factory.NewOptionalCallback(method, a)) {
+    if (this->failed())
+      RunCallback(PP_ERROR_BADARGUMENT);
+  }
+
+  // For callbacks that take two extra parameters as a closure.
+  template<class CallbackFactory, typename Method, typename A, typename B>
+  EnterHostFunctionForceCallback(PP_Instance instance,
+                                 CallbackFactory& factory,
+                                 Method method,
+                                 const A& a,
+                                 const B& b)
+      : thunk::EnterFunctionNoLock<FunctionT>(instance),
+        needs_running_(true),
+        callback_(factory.NewOptionalCallback(method, a, b)) {
+    if (this->failed())
+      RunCallback(PP_ERROR_BADARGUMENT);
+  }
+
+  ~EnterHostFunctionForceCallback() {
+    if (needs_running_) {
+      NOTREACHED() << "Should always call SetResult except in the "
+                      "initialization failed case.";
+      RunCallback(PP_ERROR_FAILED);
+    }
+  }
+
+  void SetResult(int32_t result) {
+    DCHECK(needs_running_) << "Don't call SetResult when there already is one.";
+    needs_running_ = false;
+    if (result != PP_OK_COMPLETIONPENDING)
+      callback_.Run(result);
+  }
+
+  PP_CompletionCallback callback() {
+    return callback_.pp_completion_callback();
+  }
+
+ private:
+  void RunCallback(int32_t result) {
+    DCHECK(needs_running_);
+    needs_running_ = false;
+    callback_.Run(result);
+  }
+
+  bool needs_running_;
+  pp::CompletionCallback callback_;
+};
+
 }  // namespace proxy
 }  // namespace ppapi