Inline small constructors of CallbackBase

Some of CallbackBase constructors has small bodies that is even smaller
than their size of the invocation set up.
This CL marks such constructors as inline for smaller binary size, and
reduces the stripped binary size of chrome on linux by 156kB.

Change-Id: I95999f4aebda6bc886dcfb66bc284ec0d42ccc86
Reviewed-on: https://chromium-review.googlesource.com/1113088
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#570053}

base/callback_internal.cc

@@ -33,7 +33,6 @@ BindStateBase::BindStateBase(InvokeFuncStorage polymorphic_invoke,
       destructor_(destructor),
       is_cancelled_(is_cancelled) {}
 
-CallbackBase::CallbackBase(CallbackBase&& c) noexcept = default;
 CallbackBase& CallbackBase::operator=(CallbackBase&& c) noexcept = default;
 CallbackBase::CallbackBase(const CallbackBaseCopyable& c)
     : bind_state_(c.bind_state_) {}
@@ -66,21 +65,12 @@ bool CallbackBase::EqualsInternal(const CallbackBase& other) const {
   return bind_state_ == other.bind_state_;
 }
 
-CallbackBase::CallbackBase(BindStateBase* bind_state)
-    : bind_state_(bind_state ? AdoptRef(bind_state) : nullptr) {
-  DCHECK(!bind_state_.get() || bind_state_->HasOneRef());
-}
-
 CallbackBase::~CallbackBase() = default;
 
-CallbackBaseCopyable::CallbackBaseCopyable(const CallbackBaseCopyable& c)
-    : CallbackBase(nullptr) {
+CallbackBaseCopyable::CallbackBaseCopyable(const CallbackBaseCopyable& c) {
   bind_state_ = c.bind_state_;
 }
 
-CallbackBaseCopyable::CallbackBaseCopyable(CallbackBaseCopyable&& c) noexcept =
-    default;
-
 CallbackBaseCopyable& CallbackBaseCopyable::operator=(
     const CallbackBaseCopyable& c) {
   bind_state_ = c.bind_state_;

base/callback_internal.h

@@ -108,7 +108,7 @@ class BASE_EXPORT BindStateBase
 // CallbackBase<Copyable> uses CallbackBase<MoveOnly> for its implementation.
 class BASE_EXPORT CallbackBase {
  public:
-  CallbackBase(CallbackBase&& c) noexcept;
+  inline CallbackBase(CallbackBase&& c) noexcept;
   CallbackBase& operator=(CallbackBase&& c) noexcept;
 
   explicit CallbackBase(const CallbackBaseCopyable& c);
@@ -138,7 +138,7 @@ class BASE_EXPORT CallbackBase {
 
   // Allow initializing of |bind_state_| via the constructor to avoid default
   // initialization of the scoped_refptr.
-  explicit CallbackBase(BindStateBase* bind_state);
+  explicit inline CallbackBase(BindStateBase* bind_state);
 
   InvokeFuncStorage polymorphic_invoke() const {
     return bind_state_->polymorphic_invoke_;
@@ -153,12 +153,15 @@ class BASE_EXPORT CallbackBase {
 };
 
 constexpr CallbackBase::CallbackBase() = default;
+CallbackBase::CallbackBase(CallbackBase&&) noexcept = default;
+CallbackBase::CallbackBase(BindStateBase* bind_state)
+    : bind_state_(AdoptRef(bind_state)) {}
 
 // CallbackBase<Copyable> is a direct base class of Copyable Callbacks.
 class BASE_EXPORT CallbackBaseCopyable : public CallbackBase {
  public:
   CallbackBaseCopyable(const CallbackBaseCopyable& c);
-  CallbackBaseCopyable(CallbackBaseCopyable&& c) noexcept;
+  CallbackBaseCopyable(CallbackBaseCopyable&& c) noexcept = default;
   CallbackBaseCopyable& operator=(const CallbackBaseCopyable& c);
   CallbackBaseCopyable& operator=(CallbackBaseCopyable&& c) noexcept;