Added move constructor to PassRefPtr.

This is the first step in making PassRefPtr move only,
in preparation for removal of PassRefPtr.

BUG=640449

Review-Url: https://codereview.chromium.org/2274793002
Cr-Commit-Position: refs/heads/master@{#415123}

third_party/WebKit/Source/wtf/PassRefPtr.h

@@ -69,6 +69,7 @@ public:
     // PassRefPtr temporaries, and we don't have a need to use real const
     // PassRefPtrs anyway.
     PassRefPtr(const PassRefPtr& o) : m_ptr(o.leakRef()) {}
+    PassRefPtr(PassRefPtr&& o) : m_ptr(o.leakRef()) {}
     template <typename U> PassRefPtr(const PassRefPtr<U>& o, EnsurePtrConvertibleArgDecl(U, T)) : m_ptr(o.leakRef()) {}
 
     ALWAYS_INLINE ~PassRefPtr() { derefIfNotNull(m_ptr); }

third_party/WebKit/Source/wtf/PassRefPtrTest.cpp

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "wtf/PassRefPtr.h"
+
+#include "testing/gtest/include/gtest/gtest.h"
+#include "wtf/RefCounted.h"
+
+namespace WTF {
+
+class RefCountedClass : public RefCounted<RefCountedClass> {
+};
+
+TEST(PassRefPtrTest, MoveConstructor)
+{
+    PassRefPtr<RefCountedClass> oldPassRefPtr = adoptRef(new RefCountedClass());
+    RefCountedClass* rawPtr = oldPassRefPtr.get();
+    EXPECT_EQ(rawPtr->refCount(), 1);
+    PassRefPtr<RefCountedClass> newPassRefPtr(std::move(oldPassRefPtr));
+    EXPECT_EQ(oldPassRefPtr.get(), nullptr);
+    EXPECT_EQ(newPassRefPtr.get(), rawPtr);
+    EXPECT_EQ(rawPtr->refCount(), 1);
+}
+
+} // namespace WTF

third_party/WebKit/Source/wtf/wtf.gypi

@@ -216,6 +216,7 @@
             'MakeCancellableTest.cpp',
             'MathExtrasTest.cpp',
             'OptionalTest.cpp',
+            'PassRefPtrTest.cpp',
             'RefPtrTest.cpp',
             'SaturatedArithmeticTest.cpp',
             'StringExtrasTest.cpp',