Implement generic CreateCopyResultCallback and RunAndQuit.

chrome/browser/google_apis/test_util.h

Index: chrome/browser/google_apis/test_util.h
diff --git a/chrome/browser/google_apis/test_util.h b/chrome/browser/google_apis/test_util.h
index d76f360114ee36f398b5e28d052c56381f5815bc..8127dad9b43950652010acb423a753e0b211afb2 100644
--- a/chrome/browser/google_apis/test_util.h
+++ b/chrome/browser/google_apis/test_util.h
@@ -7,7 +7,10 @@
 
 #include <string>
 
+#include "base/bind.h"
+#include "base/callback.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/template_util.h"
 #include "chrome/browser/google_apis/gdata_errorcode.h"
 
 class GURL;
@@ -43,6 +46,9 @@ namespace test_util {
 // repeatedly.
 void RunBlockingPoolTask();
 
+// Runs the closure, and then quits the current MessageLoop.
+void RunAndQuit(const base::Closure& closure);
+
 // Removes |prefix| from |input| and stores the result in |output|. Returns
 // true if the prefix is removed.
 bool RemovePrefix(const std::string& input,
@@ -185,6 +191,135 @@ bool ParseContentRangeHeader(const std::string& value,
                              int64* end_position,
                              int64* length);
 
+// Google API related code and Drive File System code work on asynchronous
+// architecture and return the results via callbacks.
+// Following code implements a callback to copy such results.
+// Here is how to use:
+//
+//   // Prepare result storage.
+//   ResultType1 result1;
+//   ResultType2 result2;
+//           :
+//
+//   PerformAsynchronousTask(
+//       param1, param2, ...,
+//       CreateCopyResultCallback(&result1, &result2, ...));
+//   RunBlockingPoolTask();  // Run message loop to complete the async task.
+//
+//   // Hereafter, we can write expectation with results.
+//   EXPECT_EQ(expected_result1, result1);
+//   EXPECT_EQ(expected_result2, result2);
+//                     :
+//
+// Note: The max arity of the supported function is 3. The limitation comes
+//   from the max arity of base::Callback, which is 7. A created callback
+//   consumes two arguments for each input type.
+// TODO(hidehiko): Use replace CopyResultFromXxxCallback method defined above
+//   by this one. (crbug.com/180569).
+namespace internal {
+// Following helper templates are to support Chrome's move semantics.
+// Their goal is defining helper methods which are similar to:
+//   void CopyResultCallback1(T1* out1, T1&& in1)
+//   void CopyResultCallback2(T1* out1, T2* out2, T1&& in1, T2&& in2)
+//            :
+// in C++11.
+
+// Declare if the type is movable or not. Currently limited to scoped_ptr only.
+// We can add more types upon the usage.
+template<typename T> struct IsMovable : base::false_type {};
+template<typename T, typename D>
+struct IsMovable<scoped_ptr<T, D> > : base::true_type {};
+
+// InType is const T& if |UseConstRef| is true, otherwise |T|.
+template<bool UseConstRef, typename T> struct InTypeHelper {
+  typedef const T& InType;
+};
+template<typename T> struct InTypeHelper<false, T> {
+  typedef T InType;
+};
+
+// Simulates the std::move operation in C++11. We use pointer here for argument,
+// instead of rvalue reference.
+template<bool IsMovable, typename T> struct MoveHelper {
+  static const T& Move(const T* in) { return *in; }
+};
+template<typename T> struct MoveHelper<true, T> {
+  static T Move(T* in) { return in->Pass(); }
+};
+
+// Helper to handle Chrome's move semantics correctly.
+template<typename T>
+struct CopyResultCallbackHelper
+      // It is necessary to calculate the exact signature of callbacks we want
+      // to create here. In our case, as we use value-parameters for primitive
+      // types and movable types in the callback declaration.
+      // Thus the incoming type is as follows:
+      // 1) If the argument type |T| is class type but doesn't movable,
+      //    |InType| is const T&.
+      // 2) Otherwise, |T| as is.
+    : InTypeHelper<
+          base::is_class<T>::value && !IsMovable<T>::value,  // UseConstRef
+          T>,
+      MoveHelper<IsMovable<T>::value, T> {
+};
+
+// Copies the |in|'s value to |out|.
+template<typename T1>
+void CopyResultCallback(
+    T1* out,
+    typename CopyResultCallbackHelper<T1>::InType in) {
+  *out = CopyResultCallbackHelper<T1>::Move(&in);
+}
+
+// Copies the |in1|'s value to |out1|, and |in2|'s to |out2|.
+template<typename T1, typename T2>
+void CopyResultCallback(
+    T1* out1,
+    T2* out2,
+    typename CopyResultCallbackHelper<T1>::InType in1,
+    typename CopyResultCallbackHelper<T2>::InType in2) {
+  *out1 = CopyResultCallbackHelper<T1>::Move(&in1);
+  *out2 = CopyResultCallbackHelper<T2>::Move(&in2);
+}
+
+// Copies the |in1|'s value to |out1|, |in2|'s to |out2|, and |in3|'s to |out3|.
+template<typename T1, typename T2, typename T3>
+void CopyResultCallback(
+    T1* out1,
+    T2* out2,
+    T3* out3,
+    typename CopyResultCallbackHelper<T1>::InType in1,
+    typename CopyResultCallbackHelper<T2>::InType in2,
+    typename CopyResultCallbackHelper<T3>::InType in3) {
+  *out1 = CopyResultCallbackHelper<T1>::Move(&in1);
+  *out2 = CopyResultCallbackHelper<T2>::Move(&in2);
+  *out3 = CopyResultCallbackHelper<T3>::Move(&in3);
+}
+
+}  // namespace internal
+
+template<typename T1>
+base::Callback<void(typename internal::CopyResultCallbackHelper<T1>::InType)>
+CreateCopyResultCallback(T1* out1) {
+  return base::Bind(&internal::CopyResultCallback<T1>, out1);
+}
+
+template<typename T1, typename T2>
+base::Callback<void(typename internal::CopyResultCallbackHelper<T1>::InType,
+                    typename internal::CopyResultCallbackHelper<T2>::InType)>
+CreateCopyResultCallback(T1* out1, T2* out2) {
+  return base::Bind(&internal::CopyResultCallback<T1, T2>, out1, out2);
+}
+
+template<typename T1, typename T2, typename T3>
+base::Callback<void(typename internal::CopyResultCallbackHelper<T1>::InType,
+                    typename internal::CopyResultCallbackHelper<T2>::InType,
+                    typename internal::CopyResultCallbackHelper<T3>::InType)>
+CreateCopyResultCallback(T1* out1, T2* out2, T3* out3) {
+  return base::Bind(
+      &internal::CopyResultCallback<T1, T2, T3>, out1, out2, out3);
+}
+
 }  // namespace test_util
 }  // namespace google_apis