base: Change DCHECK_IS_ON to a macro DCHECK_IS_ON().

This ensures that if the header is not included, and a DCHECK is guarded
by this check, that the file will fail to compile instead of silently
compiling the DCHECK out.

For example:

#if DCHECK_IS_ON
DCHECK(SomeThing());
#endif

This example would be compiled out if DCHECK_IS_ON was not defined due
to not including the logging.h header.

Instead, this will fail to compile:

#if DCHECK_IS_ON()
DCHECK(SomeThing());
#endif

R=thakis@chromium.org

Review URL: https://codereview.chromium.org/842523002

Cr-Commit-Position: refs/heads/master@{#310626}


CrOS-Libchrome-Original-Commit: e649f573a38b00bb20fe0925098251a4ff184566
diff --git a/base/logging_unittest.cc b/base/logging_unittest.cc
index 6ee4e76..8b9701a 100644
--- a/base/logging_unittest.cc
+++ b/base/logging_unittest.cc
@@ -187,7 +187,7 @@
 TEST_F(LoggingTest, DcheckStreamsAreLazy) {
   MockLogSource mock_log_source;
   EXPECT_CALL(mock_log_source, Log()).Times(0);
-#if DCHECK_IS_ON
+#if DCHECK_IS_ON()
   DCHECK(true) << mock_log_source.Log();
   DCHECK_EQ(0, 0) << mock_log_source.Log();
 #else
@@ -202,27 +202,27 @@
 TEST_F(LoggingTest, Dcheck) {
 #if defined(NDEBUG) && !defined(DCHECK_ALWAYS_ON)
   // Release build.
-  EXPECT_FALSE(DCHECK_IS_ON);
+  EXPECT_FALSE(DCHECK_IS_ON());
   EXPECT_FALSE(DLOG_IS_ON(DCHECK));
 #elif defined(NDEBUG) && defined(DCHECK_ALWAYS_ON)
   // Release build with real DCHECKS.
   SetLogAssertHandler(&LogSink);
-  EXPECT_TRUE(DCHECK_IS_ON);
+  EXPECT_TRUE(DCHECK_IS_ON());
   EXPECT_FALSE(DLOG_IS_ON(DCHECK));
 #else
   // Debug build.
   SetLogAssertHandler(&LogSink);
-  EXPECT_TRUE(DCHECK_IS_ON);
+  EXPECT_TRUE(DCHECK_IS_ON());
   EXPECT_TRUE(DLOG_IS_ON(DCHECK));
 #endif
 
   EXPECT_EQ(0, log_sink_call_count);
   DCHECK(false);
-  EXPECT_EQ(DCHECK_IS_ON ? 1 : 0, log_sink_call_count);
+  EXPECT_EQ(DCHECK_IS_ON() ? 1 : 0, log_sink_call_count);
   DPCHECK(false);
-  EXPECT_EQ(DCHECK_IS_ON ? 2 : 0, log_sink_call_count);
+  EXPECT_EQ(DCHECK_IS_ON() ? 2 : 0, log_sink_call_count);
   DCHECK_EQ(0, 1);
-  EXPECT_EQ(DCHECK_IS_ON ? 3 : 0, log_sink_call_count);
+  EXPECT_EQ(DCHECK_IS_ON() ? 3 : 0, log_sink_call_count);
 }
 
 TEST_F(LoggingTest, DcheckReleaseBehavior) {