libchrome: Uprev the library to r405848 from Chromium

Pulled the latest and greatest version of libchrome from Chromium.

The merge was done against r405848 which corresponds to git commit
909e5d3ecab27bb09cc570c1c215d0221bd6fe53 of Jul 15, 2016

Notable changes are:
- base::Bind() now explicitly disallows captures in lambdas (which was
  never allowed in the style guide).
- base::ListValue::iterator now exposes std::unique_ptr<base::Value>
  instead of raw base::Value*.

BUG: 29104761
TEST: All tests in libchrome_test pass on dragonboard-eng build

Change-Id: I94b285a3be074efa30c4e71ae93c8f2a99fb0b87

1 files changed, 313 insertions, 308 deletions

diff --git a/base/bind_internal.h b/base/bind_internal.h
index 6e0a425eab..3d6ca09c41 100644
--- a/base/bind_internal.h
+++ b/base/bind_internal.h
@@ -7,6 +7,7 @@
 
 #include <stddef.h>
 
+#include <tuple>
 #include <type_traits>
 
 #include "base/bind_helpers.h"
@@ -17,10 +18,6 @@
 #include "base/tuple.h"
 #include "build/build_config.h"
 
-#if defined(OS_WIN)
-#include "base/bind_internal_win.h"
-#endif
-
 namespace base {
 namespace internal {
 
@@ -28,56 +25,80 @@ namespace internal {
 //
 //
 // CONCEPTS:
-//  Runnable -- A type (really a type class) that has a single Run() method
-//              and a RunType typedef that corresponds to the type of Run().
-//              A Runnable can declare that it should treated like a method
-//              call by including a typedef named IsMethod.  The value of
-//              this typedef is NOT inspected, only the existence.  When a
-//              Runnable declares itself a method, Bind() will enforce special
-//              refcounting + WeakPtr handling semantics for the first
-//              parameter which is expected to be an object.
-//  Functor -- A copyable type representing something that should be called.
-//             All function pointers, Callback<>, and Runnables are functors
-//             even if the invocation syntax differs.
+//  Functor -- A movable type representing something that should be called.
+//             All function pointers and Callback<> are functors even if the
+//             invocation syntax differs.
 //  RunType -- A function type (as opposed to function _pointer_ type) for
-//             a Run() function.  Usually just a convenience typedef.
+//             a Callback<>::Run().  Usually just a convenience typedef.
 //  (Bound)Args -- A set of types that stores the arguments.
 //
 // Types:
-//  RunnableAdapter<> -- Wraps the various "function" pointer types into an
-//                       object that adheres to the Runnable interface.
 //  ForceVoidReturn<> -- Helper class for translating function signatures to
 //                       equivalent forms with a "void" return type.
-//  FunctorTraits<> -- Type traits used determine the correct RunType and
-//                     RunnableType for a Functor.  This is where function
+//  FunctorTraits<> -- Type traits used to determine the correct RunType and
+//                     invocation manner for a Functor.  This is where function
 //                     signature adapters are applied.
-//  MakeRunnable<> -- Takes a Functor and returns an object in the Runnable
-//                    type class that represents the underlying Functor.
-//  InvokeHelper<> -- Take a Runnable + arguments and actully invokes it.
+//  InvokeHelper<> -- Take a Functor + arguments and actully invokes it.
 //                    Handle the differing syntaxes needed for WeakPtr<>
-//                    support, and for ignoring return values.  This is separate
-//                    from Invoker to avoid creating multiple version of
-//                    Invoker<>.
-//  Invoker<> -- Unwraps the curried parameters and executes the Runnable.
+//                    support.  This is separate from Invoker to avoid creating
+//                    multiple version of Invoker<>.
+//  Invoker<> -- Unwraps the curried parameters and executes the Functor.
 //  BindState<> -- Stores the curried parameters, and is the main entry point
-//                 into the Bind() system, doing most of the type resolution.
-//                 There are ARITY BindState types.
+//                 into the Bind() system.
 
-// HasNonConstReferenceParam selects true_type when any of the parameters in
-// |Sig| is a non-const reference.
-// Implementation note: This non-specialized case handles zero-arity case only.
-// Non-zero-arity cases should be handled by the specialization below.
-template <typename List>
-struct HasNonConstReferenceItem : std::false_type {};
+template <typename...>
+struct make_void {
+  using type = void;
+};
 
-// Implementation note: Select true_type if the first parameter is a non-const
-// reference.  Otherwise, skip the first parameter and check rest of parameters
-// recursively.
-template <typename T, typename... Args>
-struct HasNonConstReferenceItem<TypeList<T, Args...>>
-    : std::conditional<is_non_const_reference<T>::value,
-                       std::true_type,
-                       HasNonConstReferenceItem<TypeList<Args...>>>::type {};
+// A clone of C++17 std::void_t.
+// Unlike the original version, we need |make_void| as a helper struct to avoid
+// a C++14 defect.
+// ref: http://en.cppreference.com/w/cpp/types/void_t
+// ref: http://open-std.org/JTC1/SC22/WG21/docs/cwg_defects.html#1558
+template <typename... Ts>
+using void_t = typename make_void<Ts...>::type;
+
+template <typename Callable,
+          typename Signature = decltype(&Callable::operator())>
+struct ExtractCallableRunTypeImpl;
+
+template <typename Callable, typename R, typename... Args>
+struct ExtractCallableRunTypeImpl<Callable, R(Callable::*)(Args...) const> {
+  using Type = R(Args...);
+};
+
+// Evaluated to RunType of the given callable type.
+// Example:
+//   auto f = [](int, char*) { return 0.1; };
+//   ExtractCallableRunType<decltype(f)>
+//   is evaluated to
+//   double(int, char*);
+template <typename Callable>
+using ExtractCallableRunType =
+    typename ExtractCallableRunTypeImpl<Callable>::Type;
+
+// IsConvertibleToRunType<Functor> is std::true_type if |Functor| has operator()
+// and convertible to the corresponding function pointer. Otherwise, it's
+// std::false_type.
+// Example:
+//   IsConvertibleToRunType<void(*)()>::value is false.
+//
+//   struct Foo {};
+//   IsConvertibleToRunType<void(Foo::*)()>::value is false.
+//
+//   auto f = []() {};
+//   IsConvertibleToRunType<decltype(f)>::value is true.
+//
+//   int i = 0;
+//   auto g = [i]() {};
+//   IsConvertibleToRunType<decltype(g)>::value is false.
+template <typename Functor, typename SFINAE = void>
+struct IsConvertibleToRunType : std::false_type {};
+
+template <typename Callable>
+struct IsConvertibleToRunType<Callable, void_t<decltype(&Callable::operator())>>
+    : std::is_convertible<Callable, ExtractCallableRunType<Callable>*> {};
 
 // HasRefCountedTypeAsRawPtr selects true_type when any of the |Args| is a raw
 // pointer to a RefCounted type.
@@ -95,354 +116,338 @@ struct HasRefCountedTypeAsRawPtr<T, Args...>
                        std::true_type,
                        HasRefCountedTypeAsRawPtr<Args...>>::type {};
 
-// BindsArrayToFirstArg selects true_type when |is_method| is true and the first
-// item of |Args| is an array type.
-// Implementation note: This non-specialized case handles !is_method case and
-// zero-arity case only.  Other cases should be handled by the specialization
-// below.
-template <bool is_method, typename... Args>
-struct BindsArrayToFirstArg : std::false_type {};
-
-template <typename T, typename... Args>
-struct BindsArrayToFirstArg<true, T, Args...>
-    : std::is_array<typename std::remove_reference<T>::type> {};
-
-// HasRefCountedParamAsRawPtr is the same to HasRefCountedTypeAsRawPtr except
-// when |is_method| is true HasRefCountedParamAsRawPtr skips the first argument.
-// Implementation note: This non-specialized case handles !is_method case and
-// zero-arity case only.  Other cases should be handled by the specialization
-// below.
-template <bool is_method, typename... Args>
-struct HasRefCountedParamAsRawPtr : HasRefCountedTypeAsRawPtr<Args...> {};
+// ForceVoidReturn<>
+//
+// Set of templates that support forcing the function return type to void.
+template <typename Sig>
+struct ForceVoidReturn;
 
-template <typename T, typename... Args>
-struct HasRefCountedParamAsRawPtr<true, T, Args...>
-    : HasRefCountedTypeAsRawPtr<Args...> {};
+template <typename R, typename... Args>
+struct ForceVoidReturn<R(Args...)> {
+  using RunType = void(Args...);
+};
 
-// RunnableAdapter<>
-//
-// The RunnableAdapter<> templates provide a uniform interface for invoking
-// a function pointer, method pointer, or const method pointer. The adapter
-// exposes a Run() method with an appropriate signature. Using this wrapper
-// allows for writing code that supports all three pointer types without
-// undue repetition.  Without it, a lot of code would need to be repeated 3
-// times.
-//
-// For method pointers and const method pointers the first argument to Run()
-// is considered to be the received of the method.  This is similar to STL's
-// mem_fun().
-//
-// This class also exposes a RunType typedef that is the function type of the
-// Run() function.
+// FunctorTraits<>
 //
-// If and only if the wrapper contains a method or const method pointer, an
-// IsMethod typedef is exposed.  The existence of this typedef (NOT the value)
-// marks that the wrapper should be considered a method wrapper.
+// See description at top of file.
+template <typename Functor, typename SFINAE = void>
+struct FunctorTraits;
 
+// For a callable type that is convertible to the corresponding function type.
+// This specialization is intended to allow binding captureless lambdas by
+// base::Bind(), based on the fact that captureless lambdas can be convertible
+// to the function type while capturing lambdas can't.
 template <typename Functor>
-class RunnableAdapter;
+struct FunctorTraits<
+    Functor,
+    typename std::enable_if<IsConvertibleToRunType<Functor>::value>::type> {
+  using RunType = ExtractCallableRunType<Functor>;
+  static constexpr bool is_method = false;
+  static constexpr bool is_nullable = false;
 
-// Function.
+  template <typename... RunArgs>
+  static ExtractReturnType<RunType>
+  Invoke(const Functor& functor, RunArgs&&... args) {
+    return functor(std::forward<RunArgs>(args)...);
+  }
+};
+
+// For functions.
 template <typename R, typename... Args>
-class RunnableAdapter<R(*)(Args...)> {
- public:
-  // MSVC 2013 doesn't support Type Alias of function types.
-  // Revisit this after we update it to newer version.
-  typedef R RunType(Args...);
+struct FunctorTraits<R (*)(Args...)> {
+  using RunType = R(Args...);
+  static constexpr bool is_method = false;
+  static constexpr bool is_nullable = true;
 
-  explicit RunnableAdapter(R(*function)(Args...))
-      : function_(function) {
+  template <typename... RunArgs>
+  static R Invoke(R (*function)(Args...), RunArgs&&... args) {
+    return function(std::forward<RunArgs>(args)...);
   }
+};
+
+#if defined(OS_WIN) && !defined(ARCH_CPU_X86_64)
+
+// For functions.
+template <typename R, typename... Args>
+struct FunctorTraits<R(__stdcall*)(Args...)> {
+  using RunType = R(Args...);
+  static constexpr bool is_method = false;
+  static constexpr bool is_nullable = true;
 
   template <typename... RunArgs>
-  R Run(RunArgs&&... args) {
-    return function_(std::forward<RunArgs>(args)...);
+  static R Invoke(R(__stdcall* function)(Args...), RunArgs&&... args) {
+    return function(std::forward<RunArgs>(args)...);
   }
-
- private:
-  R (*function_)(Args...);
 };
 
-// Method.
-template <typename R, typename T, typename... Args>
-class RunnableAdapter<R(T::*)(Args...)> {
- public:
-  // MSVC 2013 doesn't support Type Alias of function types.
-  // Revisit this after we update it to newer version.
-  typedef R RunType(T*, Args...);
-  using IsMethod = std::true_type;
+// For functions.
+template <typename R, typename... Args>
+struct FunctorTraits<R(__fastcall*)(Args...)> {
+  using RunType = R(Args...);
+  static constexpr bool is_method = false;
+  static constexpr bool is_nullable = true;
 
-  explicit RunnableAdapter(R(T::*method)(Args...))
-      : method_(method) {
+  template <typename... RunArgs>
+  static R Invoke(R(__fastcall* function)(Args...), RunArgs&&... args) {
+    return function(std::forward<RunArgs>(args)...);
   }
+};
 
-  template <typename Receiver, typename... RunArgs>
-  R Run(Receiver&& receiver_ptr, RunArgs&&... args) {
+#endif  // defined(OS_WIN) && !defined(ARCH_CPU_X86_64)
+
+// For methods.
+template <typename R, typename Receiver, typename... Args>
+struct FunctorTraits<R (Receiver::*)(Args...)> {
+  using RunType = R(Receiver*, Args...);
+  static constexpr bool is_method = true;
+  static constexpr bool is_nullable = true;
+
+  template <typename ReceiverPtr, typename... RunArgs>
+  static R Invoke(R (Receiver::*method)(Args...),
+                  ReceiverPtr&& receiver_ptr,
+                  RunArgs&&... args) {
     // Clang skips CV qualifier check on a method pointer invocation when the
     // receiver is a subclass. Store the receiver into a const reference to
     // T to ensure the CV check works.
     // https://llvm.org/bugs/show_bug.cgi?id=27037
-    T& receiver = *receiver_ptr;
-    return (receiver.*method_)(std::forward<RunArgs>(args)...);
+    Receiver& receiver = *receiver_ptr;
+    return (receiver.*method)(std::forward<RunArgs>(args)...);
   }
-
- private:
-  R (T::*method_)(Args...);
 };
 
-// Const Method.
-template <typename R, typename T, typename... Args>
-class RunnableAdapter<R(T::*)(Args...) const> {
- public:
-  using RunType = R(const T*, Args...);
-  using IsMethod = std::true_type;
-
-  explicit RunnableAdapter(R(T::*method)(Args...) const)
-      : method_(method) {
-  }
-
-  template <typename Receiver, typename... RunArgs>
-  R Run(Receiver&& receiver_ptr, RunArgs&&... args) {
+// For const methods.
+template <typename R, typename Receiver, typename... Args>
+struct FunctorTraits<R (Receiver::*)(Args...) const> {
+  using RunType = R(const Receiver*, Args...);
+  static constexpr bool is_method = true;
+  static constexpr bool is_nullable = true;
+
+  template <typename ReceiverPtr, typename... RunArgs>
+  static R Invoke(R (Receiver::*method)(Args...) const,
+                  ReceiverPtr&& receiver_ptr,
+                  RunArgs&&... args) {
     // Clang skips CV qualifier check on a method pointer invocation when the
-    // receiver is a subclass. Store the receiver into a unqualified reference
-    // to T to ensure the CV check works.
+    // receiver is a subclass. Store the receiver into a const reference to
+    // T to ensure the CV check works.
     // https://llvm.org/bugs/show_bug.cgi?id=27037
-    const T& receiver = *receiver_ptr;
-    return (receiver.*method_)(std::forward<RunArgs>(args)...);
+    const Receiver& receiver = *receiver_ptr;
+    return (receiver.*method)(std::forward<RunArgs>(args)...);
   }
-
- private:
-  R (T::*method_)(Args...) const;
 };
 
-
-// ForceVoidReturn<>
-//
-// Set of templates that support forcing the function return type to void.
-template <typename Sig>
-struct ForceVoidReturn;
-
-template <typename R, typename... Args>
-struct ForceVoidReturn<R(Args...)> {
-  // MSVC 2013 doesn't support Type Alias of function types.
-  // Revisit this after we update it to newer version.
-  typedef void RunType(Args...);
-};
-
-
-// FunctorTraits<>
-//
-// See description at top of file.
+// For IgnoreResults.
 template <typename T>
-struct FunctorTraits {
-  using RunnableType = RunnableAdapter<T>;
-  using RunType = typename RunnableType::RunType;
-};
-
-template <typename T>
-struct FunctorTraits<IgnoreResultHelper<T>> {
-  using RunnableType = typename FunctorTraits<T>::RunnableType;
+struct FunctorTraits<IgnoreResultHelper<T>> : FunctorTraits<T> {
   using RunType =
-      typename ForceVoidReturn<typename RunnableType::RunType>::RunType;
-};
+      typename ForceVoidReturn<typename FunctorTraits<T>::RunType>::RunType;
 
-template <typename T>
-struct FunctorTraits<Callback<T>> {
-  using RunnableType = Callback<T> ;
-  using RunType = typename Callback<T>::RunType;
+  template <typename IgnoreResultType, typename... RunArgs>
+  static void Invoke(IgnoreResultType&& ignore_result_helper,
+                     RunArgs&&... args) {
+    FunctorTraits<T>::Invoke(ignore_result_helper.functor_,
+                             std::forward<RunArgs>(args)...);
+  }
 };
 
-
-// MakeRunnable<>
-//
-// Converts a passed in functor to a RunnableType using type inference.
-
-template <typename T>
-typename FunctorTraits<T>::RunnableType MakeRunnable(const T& t) {
-  return RunnableAdapter<T>(t);
-}
-
-template <typename T>
-typename FunctorTraits<T>::RunnableType
-MakeRunnable(const IgnoreResultHelper<T>& t) {
-  return MakeRunnable(t.functor_);
-}
-
-template <typename T>
-const typename FunctorTraits<Callback<T>>::RunnableType&
-MakeRunnable(const Callback<T>& t) {
-  DCHECK(!t.is_null());
-  return t;
-}
-
+// For Callbacks.
+template <typename R, typename... Args, CopyMode copy_mode>
+struct FunctorTraits<Callback<R(Args...), copy_mode>> {
+  using RunType = R(Args...);
+  static constexpr bool is_method = false;
+  static constexpr bool is_nullable = true;
+
+  template <typename CallbackType, typename... RunArgs>
+  static R Invoke(CallbackType&& callback, RunArgs&&... args) {
+    DCHECK(!callback.is_null());
+    return std::forward<CallbackType>(callback).Run(
+        std::forward<RunArgs>(args)...);
+  }
+};
 
 // InvokeHelper<>
 //
-// There are 3 logical InvokeHelper<> specializations: normal, void-return,
-// WeakCalls.
+// There are 2 logical InvokeHelper<> specializations: normal, WeakCalls.
 //
 // The normal type just calls the underlying runnable.
 //
-// We need a InvokeHelper to handle void return types in order to support
-// IgnoreResult().  Normally, if the Runnable's RunType had a void return,
-// the template system would just accept "return functor.Run()" ignoring
-// the fact that a void function is being used with return. This piece of
-// sugar breaks though when the Runnable's RunType is not void.  Thus, we
-// need a partial specialization to change the syntax to drop the "return"
-// from the invocation call.
-//
-// WeakCalls similarly need special syntax that is applied to the first
-// argument to check if they should no-op themselves.
-template <bool IsWeakCall, typename ReturnType, typename Runnable>
+// WeakCalls need special syntax that is applied to the first argument to check
+// if they should no-op themselves.
+template <bool is_weak_call, typename ReturnType>
 struct InvokeHelper;
 
-template <typename ReturnType, typename Runnable>
-struct InvokeHelper<false, ReturnType, Runnable> {
-  template <typename... RunArgs>
-  static ReturnType MakeItSo(Runnable runnable, RunArgs&&... args) {
-    return runnable.Run(std::forward<RunArgs>(args)...);
-  }
-};
-
-template <typename Runnable>
-struct InvokeHelper<false, void, Runnable> {
-  template <typename... RunArgs>
-  static void MakeItSo(Runnable runnable, RunArgs&&... args) {
-    runnable.Run(std::forward<RunArgs>(args)...);
+template <typename ReturnType>
+struct InvokeHelper<false, ReturnType> {
+  template <typename Functor, typename... RunArgs>
+  static inline ReturnType MakeItSo(Functor&& functor, RunArgs&&... args) {
+    using Traits = FunctorTraits<typename std::decay<Functor>::type>;
+    return Traits::Invoke(std::forward<Functor>(functor),
+                          std::forward<RunArgs>(args)...);
   }
 };
 
-template <typename Runnable>
-struct InvokeHelper<true, void, Runnable> {
-  template <typename BoundWeakPtr, typename... RunArgs>
-  static void MakeItSo(Runnable runnable,
-                       BoundWeakPtr weak_ptr,
-                       RunArgs&&... args) {
-    if (!weak_ptr.get()) {
-      return;
-    }
-    runnable.Run(weak_ptr.get(), std::forward<RunArgs>(args)...);
-  }
-};
-
-#if !defined(_MSC_VER)
-
-template <typename ReturnType, typename Runnable>
-struct InvokeHelper<true, ReturnType, Runnable> {
+template <typename ReturnType>
+struct InvokeHelper<true, ReturnType> {
   // WeakCalls are only supported for functions with a void return type.
   // Otherwise, the function result would be undefined if the the WeakPtr<>
   // is invalidated.
   static_assert(std::is_void<ReturnType>::value,
                 "weak_ptrs can only bind to methods without return values");
-};
 
-#endif
+  template <typename Functor, typename BoundWeakPtr, typename... RunArgs>
+  static inline void MakeItSo(Functor&& functor,
+                              BoundWeakPtr&& weak_ptr,
+                              RunArgs&&... args) {
+    if (!weak_ptr)
+      return;
+    using Traits = FunctorTraits<typename std::decay<Functor>::type>;
+    Traits::Invoke(std::forward<Functor>(functor),
+                   std::forward<BoundWeakPtr>(weak_ptr),
+                   std::forward<RunArgs>(args)...);
+  }
+};
 
 // Invoker<>
 //
 // See description at the top of the file.
-template <typename BoundIndices, typename StorageType,
-          typename InvokeHelperType, typename UnboundForwardRunType>
+template <typename StorageType, typename UnboundRunType>
 struct Invoker;
 
-template <size_t... bound_indices,
-          typename StorageType,
-          typename InvokeHelperType,
-          typename R,
-          typename... UnboundArgs>
-struct Invoker<IndexSequence<bound_indices...>,
-               StorageType,
-               InvokeHelperType,
-               R(UnboundArgs...)> {
+template <typename StorageType, typename R, typename... UnboundArgs>
+struct Invoker<StorageType, R(UnboundArgs...)> {
   static R Run(BindStateBase* base, UnboundArgs&&... unbound_args) {
-    StorageType* storage = static_cast<StorageType*>(base);
     // Local references to make debugger stepping easier. If in a debugger,
     // you really want to warp ahead and step through the
     // InvokeHelper<>::MakeItSo() call below.
-    return InvokeHelperType::MakeItSo(
-        storage->runnable_, Unwrap(get<bound_indices>(storage->bound_args_))...,
-        std::forward<UnboundArgs>(unbound_args)...);
+    const StorageType* storage = static_cast<StorageType*>(base);
+    static constexpr size_t num_bound_args =
+        std::tuple_size<decltype(storage->bound_args_)>::value;
+    return RunImpl(storage->functor_,
+                   storage->bound_args_,
+                   MakeIndexSequence<num_bound_args>(),
+                   std::forward<UnboundArgs>(unbound_args)...);
   }
-};
 
-// Used to implement MakeArgsStorage.
-template <bool is_method, typename... BoundArgs>
-struct MakeArgsStorageImpl {
-  using Type = std::tuple<BoundArgs...>;
+ private:
+  template <typename Functor, typename BoundArgsTuple, size_t... indices>
+  static inline R RunImpl(Functor&& functor,
+                          BoundArgsTuple&& bound,
+                          IndexSequence<indices...>,
+                          UnboundArgs&&... unbound_args) {
+    static constexpr bool is_method =
+        FunctorTraits<typename std::decay<Functor>::type>::is_method;
+
+    using DecayedArgsTuple = typename std::decay<BoundArgsTuple>::type;
+    static constexpr bool is_weak_call =
+        IsWeakMethod<is_method,
+                     typename std::tuple_element<
+                         indices,
+                         DecayedArgsTuple>::type...>::value;
+
+    return InvokeHelper<is_weak_call, R>::MakeItSo(
+        std::forward<Functor>(functor),
+        Unwrap(base::get<indices>(std::forward<BoundArgsTuple>(bound)))...,
+        std::forward<UnboundArgs>(unbound_args)...);
+  }
 };
 
-template <typename Obj, typename... BoundArgs>
-struct MakeArgsStorageImpl<true, Obj*, BoundArgs...> {
-  using Type = std::tuple<scoped_refptr<Obj>, BoundArgs...>;
+// Used to implement MakeUnboundRunType.
+template <typename Functor, typename... BoundArgs>
+struct MakeUnboundRunTypeImpl {
+  using RunType =
+      typename FunctorTraits<typename std::decay<Functor>::type>::RunType;
+  using ReturnType = ExtractReturnType<RunType>;
+  using Args = ExtractArgs<RunType>;
+  using UnboundArgs = DropTypeListItem<sizeof...(BoundArgs), Args>;
+  using Type = MakeFunctionType<ReturnType, UnboundArgs>;
 };
+template <typename Functor>
+typename std::enable_if<FunctorTraits<Functor>::is_nullable, bool>::type
+IsNull(const Functor& functor) {
+  return !functor;
+}
 
-// Constructs a tuple type to store BoundArgs into BindState.
-// This wraps the first argument into a scoped_refptr if |is_method| is true and
-// the first argument is a raw pointer.
-// Other arguments are adjusted for store and packed into a tuple.
-template <bool is_method, typename... BoundArgs>
-using MakeArgsStorage = typename MakeArgsStorageImpl<
-  is_method, typename std::decay<BoundArgs>::type...>::Type;
+template <typename Functor>
+typename std::enable_if<!FunctorTraits<Functor>::is_nullable, bool>::type
+IsNull(const Functor&) {
+  return false;
+}
 
 // BindState<>
 //
-// This stores all the state passed into Bind() and is also where most
-// of the template resolution magic occurs.
-//
-// Runnable is the functor we are binding arguments to.
-// RunType is type of the Run() function that the Invoker<> should use.
-// Normally, this is the same as the RunType of the Runnable, but it can
-// be different if an adapter like IgnoreResult() has been used.
-//
-// BoundArgs contains the storage type for all the bound arguments.
-template <typename Runnable, typename RunType, typename... BoundArgs>
-struct BindState;
-
-template <typename Runnable,
-          typename R,
-          typename... Args,
-          typename... BoundArgs>
-struct BindState<Runnable, R(Args...), BoundArgs...> final
-    : public BindStateBase {
- private:
-  using StorageType = BindState<Runnable, R(Args...), BoundArgs...>;
-  using RunnableType = Runnable;
+// This stores all the state passed into Bind().
+template <typename Functor, typename... BoundArgs>
+struct BindState final : BindStateBase {
+  template <typename ForwardFunctor, typename... ForwardBoundArgs>
+  explicit BindState(ForwardFunctor&& functor, ForwardBoundArgs&&... bound_args)
+      : BindStateBase(&Destroy),
+      functor_(std::forward<ForwardFunctor>(functor)),
+        bound_args_(std::forward<ForwardBoundArgs>(bound_args)...) {
+    DCHECK(!IsNull(functor_));
+  }
 
-  enum { is_method = HasIsMethodTag<Runnable>::value };
+  Functor functor_;
+  std::tuple<BoundArgs...> bound_args_;
 
-  // true_type if Runnable is a method invocation and the first bound argument
-  // is a WeakPtr.
-  using IsWeakCall =
-      IsWeakMethod<is_method, typename std::decay<BoundArgs>::type...>;
+ private:
+  ~BindState() {}
 
-  using BoundIndices = MakeIndexSequence<sizeof...(BoundArgs)>;
-  using InvokeHelperType = InvokeHelper<IsWeakCall::value, R, Runnable>;
+  static void Destroy(BindStateBase* self) {
+    delete static_cast<BindState*>(self);
+  }
+};
 
-  using UnboundArgs = DropTypeListItem<sizeof...(BoundArgs), TypeList<Args...>>;
+// Used to implement MakeBindStateType.
+template <bool is_method, typename Functor, typename... BoundArgs>
+struct MakeBindStateTypeImpl;
 
- public:
-  using UnboundRunType = MakeFunctionType<R, UnboundArgs>;
-  using InvokerType =
-      Invoker<BoundIndices, StorageType, InvokeHelperType, UnboundRunType>;
+template <typename Functor, typename... BoundArgs>
+struct MakeBindStateTypeImpl<false, Functor, BoundArgs...> {
+  static_assert(!HasRefCountedTypeAsRawPtr<BoundArgs...>::value,
+                "A parameter is a refcounted type and needs scoped_refptr.");
+  using Type = BindState<typename std::decay<Functor>::type,
+                         typename std::decay<BoundArgs>::type...>;
+};
 
-  template <typename... ForwardArgs>
-  BindState(const Runnable& runnable, ForwardArgs&&... bound_args)
-      : BindStateBase(&Destroy),
-        runnable_(runnable),
-        bound_args_(std::forward<ForwardArgs>(bound_args)...) {}
+template <typename Functor>
+struct MakeBindStateTypeImpl<true, Functor> {
+  using Type = BindState<typename std::decay<Functor>::type>;
+};
 
-  RunnableType runnable_;
-  MakeArgsStorage<is_method, BoundArgs...> bound_args_;
+template <typename Functor, typename Receiver, typename... BoundArgs>
+struct MakeBindStateTypeImpl<true, Functor, Receiver, BoundArgs...> {
+  static_assert(
+      !std::is_array<typename std::remove_reference<Receiver>::type>::value,
+      "First bound argument to a method cannot be an array.");
+  static_assert(!HasRefCountedTypeAsRawPtr<BoundArgs...>::value,
+                "A parameter is a refcounted type and needs scoped_refptr.");
 
  private:
-  ~BindState() {}
+  using DecayedReceiver = typename std::decay<Receiver>::type;
 
-  static void Destroy(BindStateBase* self) {
-    delete static_cast<BindState*>(self);
-  }
+ public:
+  using Type = BindState<
+      typename std::decay<Functor>::type,
+      typename std::conditional<
+          std::is_pointer<DecayedReceiver>::value,
+          scoped_refptr<typename std::remove_pointer<DecayedReceiver>::type>,
+          DecayedReceiver>::type,
+      typename std::decay<BoundArgs>::type...>;
 };
 
+template <typename Functor, typename... BoundArgs>
+using MakeBindStateType = typename MakeBindStateTypeImpl<
+    FunctorTraits<typename std::decay<Functor>::type>::is_method,
+    Functor,
+    BoundArgs...>::Type;
+
 }  // namespace internal
+
+// Returns a RunType of bound functor.
+// E.g. MakeUnboundRunType<R(A, B, C), A, B> is evaluated to R(C).
+template <typename Functor, typename... BoundArgs>
+using MakeUnboundRunType =
+    typename internal::MakeUnboundRunTypeImpl<Functor, BoundArgs...>::Type;
+
 }  // namespace base
 
 #endif  // BASE_BIND_INTERNAL_H_