Prioritizing input and compositor tasks in the blink scheduler.

Source/wtf/Atomics.h

Index: Source/wtf/Atomics.h
diff --git a/Source/wtf/Atomics.h b/Source/wtf/Atomics.h
index 82113f4abaa3ef8c16e71f8a4bfaefda56f44436..1c86065b4c9cf9e901835c7f8ed8bae7753ef6f1 100644
--- a/Source/wtf/Atomics.h
+++ b/Source/wtf/Atomics.h
@@ -78,6 +78,16 @@ ALWAYS_INLINE void atomicSetOneToZero(int volatile* ptr)
     InterlockedExchange(reinterpret_cast<long volatile*>(ptr), 0);
 }
 
+ALWAYS_INLINE void* atomicTestAndSwap(void* volatile* ptr, void* comprand, void* replacement)
+{
+    return InterlockedCompareExchangePointer(ptr, replacement, comprand);
+}
+
+ALWAYS_INLINE void* atomicExchange(void* volatile* ptr, void* value)
+{
+    return InterlockedExchangePointer(ptr, value);
+}
+
 #else
 
 // atomicAdd returns the result of the addition.
@@ -103,6 +113,17 @@ ALWAYS_INLINE void atomicSetOneToZero(int volatile* ptr)
     ASSERT(*ptr == 1);
     __sync_lock_release(ptr);
 }
+
+ALWAYS_INLINE void* atomicTestAndSwap(void *volatile* ptr, void* comprand, void* replacement)
+{
+    return __sync_val_compare_and_swap(ptr, comprand, replacement);
+}
+
+ALWAYS_INLINE void* atomicExchange(void *volatile* ptr, void* value)
+{
+    return __sync_lock_test_and_set(ptr, value);
+}
+
 #endif
 
 #if defined(THREAD_SANITIZER)
@@ -163,10 +184,12 @@ ALWAYS_INLINE int acquireLoad(volatile const int* ptr)
 } // namespace WTF
 
 using WTF::atomicAdd;
-using WTF::atomicSubtract;
 using WTF::atomicDecrement;
+using WTF::atomicExchange;
 using WTF::atomicIncrement;
 using WTF::atomicTestAndSetToOne;
+using WTF::atomicTestAndSwap;
+using WTF::atomicSubtract;
 using WTF::atomicSetOneToZero;
 using WTF::acquireLoad;
 using WTF::releaseStore;