Add a GN flag to allow sanitizer builds with full debugging symbols.

build/config/sanitizers/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build_overrides/build.gni")
 import("//build/config/chrome_build.gni")
 import("//build/config/chromecast_build.gni")
 import("//build/config/clang/clang.gni")
 import("//build/config/sanitizers/sanitizers.gni")
 import("//build/toolchain/toolchain.gni")
@@ skipping 259 matching lines @@
       }
     }
   }
 }
 
 config("common_sanitizer_flags") {
   cflags = []
   cflags_cc = []
 
   # Sanitizers need line table info for stack traces. They don't need type info
-  # or variable info, so we can leave that out to speed up the build.
+  # or variable info, so we can leave that out to speed up the build (unless
+  # it's explicitly asked for by setting |sanitizer_keep_symbols| to true).
   if (using_sanitizer) {
     assert(is_clang, "sanitizers only supported with clang")
+    if (!sanitizer_keep_symbols) {
+      cflags += [ "-gline-tables-only" ]
+    }
+
     cflags += [
-      "-gline-tables-only",
-
       # Column info in debug data confuses Visual Studio's debugger, so don't
       # use this by default.  However, clusterfuzz needs it for good attribution
       # of reports to CLs, so turn it on there.
       "-gcolumn-info",
     ]
   }
 
   # Common options for AddressSanitizer, LeakSanitizer, ThreadSanitizer,
   # MemorySanitizer and non-official CFI builds.
   if (using_sanitizer || (is_cfi && !is_official_build)) {
@@ skipping 289 matching lines @@
 # This allows to selectively disable ubsan_vptr, when needed. In particular,
 # if some third_party code is required to be compiled without rtti, which
 # is a requirement for ubsan_vptr.
 config("default_sanitizer_flags_but_ubsan_vptr") {
   configs = all_sanitizer_configs - [ ":ubsan_vptr_flags" ]
 }
 
 config("default_sanitizer_flags_but_coverage") {
   configs = all_sanitizer_configs - [ ":coverage_flags" ]
 }