Create sanitizer_no_symbols option.

Enabling this option prevents fuzzers/sanitizers from setting the
-gline-tables-only and -gcolumn-info flags, and instead uses the symbol
level defined by symbol_level.

This is particularly useful for reducing binary sizes when building with
use_clang_coverage=true, where stack traces are unneeded and line
numbers for coverage are determined from the coverage mappings.

Bug: 759795
Change-Id: Iae3ea9ede10281c9f29c461ed5d6eec503a661cd
Reviewed-on: https://chromium-review.googlesource.com/887285Reviewed-by: Oliver Chang <ochang@chromium.org>
Reviewed-by: Abhishek Arya <inferno@chromium.org>
Commit-Queue: Abhishek Arya <inferno@chromium.org>
Cr-Commit-Position: refs/heads/master@{#532905}

build/config/sanitizers/BUILD.gn

@@ -255,16 +255,18 @@ config("common_sanitizer_flags") {
     assert(is_clang, "sanitizers only supported with clang")
     assert(!is_official_build, "sanitizers not supported in official builds")
 
-    if (!sanitizer_keep_symbols) {
-      cflags += [ "-gline-tables-only" ]
-    }
+    if (!sanitizer_no_symbols) {
+      if (!sanitizer_keep_symbols) {
+        cflags += [ "-gline-tables-only" ]
+      }
 
-    cflags += [
-      # 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",
-    ]
+      cflags += [
+        # 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",
+      ]
+    }
 
     # Frame pointers are controlled in //build/config/compiler:default_stack_frames
   }

build/config/sanitizers/sanitizers.gni

@@ -107,6 +107,10 @@ declare_args() {
   # necessary, overriding any other symbol level arguments that may be set.
   # Setting this to true prevents this.
   sanitizer_keep_symbols = false
+
+  # Builds fuzzer/sanitizers without symbols.  Use with symbol_level=0.
+  # Useful for reducing binary size when building with use_clang_coverage=true.
+  sanitizer_no_symbols = false
 }
 
 # Disable sanitizers for non-default toolchains.