Add dvlog_always_on to enable DVLOG without DEBUG and DCHECK option

base/logging.h

Index: base/logging.h
diff --git a/base/logging.h b/base/logging.h
index 0660e7c158132abec36acd09365ec4781dcd903f..c9b7b0632ab70338fe40ea7036754c48088ebba8 100644
--- a/base/logging.h
+++ b/base/logging.h
@@ -769,9 +769,15 @@ DEFINE_CHECK_OP_IMPL(GT, > )
 #define DCHECK_IS_ON() 1
 #endif
 
+#if defined(NDEBUG) && !defined(DVLOG_ALWAYS_ON)
+#define DVLOG_IS_ON() 0
+#else
+#define DVLOG_IS_ON() 1
+#endif
+
 // Definitions for DLOG et al.
 
-#if DCHECK_IS_ON()
+#if DCHECK_IS_ON() || DVLOG_IS_ON()
 
 #define DLOG_IS_ON(severity) LOG_IS_ON(severity)
 #define DLOG_IF(severity, condition) LOG_IF(severity, condition)
@@ -780,7 +786,7 @@ DEFINE_CHECK_OP_IMPL(GT, > )
 #define DVLOG_IF(verboselevel, condition) VLOG_IF(verboselevel, condition)
 #define DVPLOG_IF(verboselevel, condition) VPLOG_IF(verboselevel, condition)
 
-#else  // DCHECK_IS_ON()
+#else  // DCHECK_IS_ON() || DVLOG_IS_ON())
 
 // If !DCHECK_IS_ON(), we want to avoid emitting any references to |condition|
 // (which may reference a variable defined only if DCHECK_IS_ON()).
@@ -793,7 +799,7 @@ DEFINE_CHECK_OP_IMPL(GT, > )
 #define DVLOG_IF(verboselevel, condition) EAT_STREAM_PARAMETERS
 #define DVPLOG_IF(verboselevel, condition) EAT_STREAM_PARAMETERS
 
-#endif  // DCHECK_IS_ON()
+#endif  // DCHECK_IS_ON() || DVLOG_IS_ON())
 
 #define DLOG(severity)                                          \
   LAZY_STREAM(LOG_STREAM(severity), DLOG_IS_ON(severity))