Add support for enabling DCHECKs in release mode

src/base/platform/elapsed-timer.h

Index: src/base/platform/elapsed-timer.h
diff --git a/src/base/platform/elapsed-timer.h b/src/base/platform/elapsed-timer.h
index dccba3a3ac29ece576f4aed63d2f9e872a1f4aab..445eed84b55be9515c4bf9041c9ba6c21f460351 100644
--- a/src/base/platform/elapsed-timer.h
+++ b/src/base/platform/elapsed-timer.h
@@ -13,7 +13,7 @@ namespace base {
 
 class ElapsedTimer FINAL {
  public:
-#ifdef DEBUG
+#if DCHECK_IS_ON
   ElapsedTimer() : started_(false) {}
 #endif
 
@@ -23,7 +23,7 @@ class ElapsedTimer FINAL {
   void Start() {
     DCHECK(!IsStarted());
     start_ticks_ = Now();
-#ifdef DEBUG
+#if DCHECK_IS_ON
     started_ = true;
 #endif
     DCHECK(IsStarted());
@@ -34,7 +34,7 @@ class ElapsedTimer FINAL {
   void Stop() {
     DCHECK(IsStarted());
     start_ticks_ = TimeTicks();
-#ifdef DEBUG
+#if DCHECK_IS_ON
     started_ = false;
 #endif
     DCHECK(!IsStarted());
@@ -87,7 +87,7 @@ class ElapsedTimer FINAL {
   }
 
   TimeTicks start_ticks_;
-#ifdef DEBUG
+#if DCHECK_IS_ON
   bool started_;
 #endif
 };