asan: Use OFFICIAL_BUILD instead of GOOGLE_CHROME_BUILD for default asan options.

GOOGLE_CHROME_BUILD is more a branding thing. Since
Google Chrome builds set both GOOGLE_CHROME_BUILD and
OFFICIAL_BUILD, this doesn't have an effect in practice.

People who do non-Google Chrome-branded OFFICIAL_BUILD
asan builds will now get the different flags, which seems
like a good change.

While here, also deduplicate the common flags and add
a comment saying that the OFFICIAL_BUILD asan flags
are basically never used.

Bug: 961769
Change-Id: I42491c1d4d3ab876b0de92d0746266580dafe1d2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1882109
Commit-Queue: Alexander Potapenko <glider@chromium.org>
Reviewed-by: Alexander Potapenko <glider@chromium.org>
Auto-Submit: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#709905}

build/sanitizers/sanitizer_options.cc

@@ -54,23 +54,19 @@ void _sanitizer_options_link_helper() { }
 //   detect_stack_use_after_return=1 - use fake stack to delay the reuse of
 //     stack allocations and detect stack-use-after-return errors.
 #if defined(OS_LINUX)
-#if defined(GOOGLE_CHROME_BUILD)
-// Default AddressSanitizer options for the official build. These do not affect
-// tests on buildbots (which don't set GOOGLE_CHROME_BUILD) or non-official
-// Chromium builds.
 const char kAsanDefaultOptions[] =
+#if defined(OFFICIAL_BUILD)
+    // Default AddressSanitizer options for the official build. These do not
+    // affect tests on buildbots (which don't set OFFICIAL_BUILD) or
+    // non-official Chromium builds. These are almost always unused, but
+    // sometimes we ship asan builds to canary.
     "legacy_pthread_cond=1 malloc_context_size=5 "
-    "symbolize=1 check_printf=1 use_sigaltstack=1 detect_leaks=0 "
-    "strip_path_prefix=/../../ fast_unwind_on_fatal=1 "
-    "allow_user_segv_handler=1 ";
 #else
-// Default AddressSanitizer options for buildbots and non-official builds.
-const char* kAsanDefaultOptions =
-    "symbolize=1 check_printf=1 use_sigaltstack=1 "
-    "detect_leaks=0 strip_path_prefix=/../../ fast_unwind_on_fatal=1 "
     "detect_stack_use_after_return=1 "
+#endif
+    "symbolize=1 check_printf=1 use_sigaltstack=1 detect_leaks=0 "
+    "strip_path_prefix=/../../ fast_unwind_on_fatal=1 "
     "allow_user_segv_handler=1 ";
-#endif  // GOOGLE_CHROME_BUILD
 
 #elif defined(OS_MACOSX)
 const char *kAsanDefaultOptions =