base: Change DCHECK_IS_ON to a macro DCHECK_IS_ON().

cc/trees/single_thread_proxy.h

Index: cc/trees/single_thread_proxy.h
diff --git a/cc/trees/single_thread_proxy.h b/cc/trees/single_thread_proxy.h
index 6f6e91f6527586e1f800f6882afa3ef43795d5bb..5092dab875e16ed34fb072bbbe4d3157dbeb70dc 100644
--- a/cc/trees/single_thread_proxy.h
+++ b/cc/trees/single_thread_proxy.h
@@ -175,13 +175,13 @@ class CC_EXPORT SingleThreadProxy : public Proxy,
 class DebugScopedSetImplThread {
  public:
   explicit DebugScopedSetImplThread(Proxy* proxy) : proxy_(proxy) {
-#if DCHECK_IS_ON
+#if !DCHECK_IS_OFF
     previous_value_ = proxy_->impl_thread_is_overridden_;
     proxy_->SetCurrentThreadIsImplThread(true);
 #endif
   }
   ~DebugScopedSetImplThread() {
-#if DCHECK_IS_ON
+#if !DCHECK_IS_OFF
     proxy_->SetCurrentThreadIsImplThread(previous_value_);
 #endif
   }
@@ -198,13 +198,13 @@ class DebugScopedSetImplThread {
 class DebugScopedSetMainThread {
  public:
   explicit DebugScopedSetMainThread(Proxy* proxy) : proxy_(proxy) {
-#if DCHECK_IS_ON
+#if !DCHECK_IS_OFF
     previous_value_ = proxy_->impl_thread_is_overridden_;
     proxy_->SetCurrentThreadIsImplThread(false);
 #endif
   }
   ~DebugScopedSetMainThread() {
-#if DCHECK_IS_ON
+#if !DCHECK_IS_OFF
     proxy_->SetCurrentThreadIsImplThread(previous_value_);
 #endif
   }