Add a |dcheck_is_configurable| build argument, independent of SyzyASAN.

Previously we gated run-time-configurable DCHECKs on the |is_syzyasan|
argument, to have them built-in to Chrome Canary SyzyASAN binaries.

We implement |dcheck_is_configurable| as a macro define rather than via
a buildflag, because Chromium currently has too many components with
undeclared dependencies on //base for introducing a new dependency of
//base/logging.h on a generated buildflags_header() to be safe.

Bug: 812058
Change-Id: Iac48c88e0c5964cc8bceac6c444e44f84133120e
Reviewed-on: https://chromium-review.googlesource.com/974904
Reviewed-by: Nick Carter <[email protected]>
Reviewed-by: Daniel Cheng <[email protected]>
Reviewed-by: Dirk Pranke <[email protected]>
Reviewed-by: Scott Violet <[email protected]>
Commit-Queue: Wez <[email protected]>
Cr-Commit-Position: refs/heads/master@{#545542}
diff --git a/chrome/browser/flag_descriptions.h b/chrome/browser/flag_descriptions.h
index 9d72490..3615ab7 100644
--- a/chrome/browser/flag_descriptions.h
+++ b/chrome/browser/flag_descriptions.h
@@ -1475,10 +1475,10 @@
 extern const char kWindows10CustomTitlebarName[];
 extern const char kWindows10CustomTitlebarDescription[];
 
-#if DCHECK_IS_ON() && defined(SYZYASAN)
-extern const char kSyzyAsanDcheckIsFatalName[];
-extern const char kSyzyAsanDcheckIsFatalDescription[];
-#endif  // DCHECK_IS_ON() && defined(SYZYASAN)
+#if DCHECK_IS_CONFIGURABLE
+extern const char kDcheckIsFatalName[];
+extern const char kDcheckIsFatalDescription[];
+#endif  // DCHECK_IS_CONFIGURABLE
 
 #endif  // defined(OS_WIN)