[Mac/GN] Use a special .symbol_resolver to help load the ASan dynamic library.

build/config/sanitizers/BUILD.gn

Index: build/config/sanitizers/BUILD.gn
diff --git a/build/config/sanitizers/BUILD.gn b/build/config/sanitizers/BUILD.gn
index dff6eb3c96612b2e294ac63f0abca1fe961e6ebc..163f9477f0abafc854781f0a9b36b2601f1401a1 100644
--- a/build/config/sanitizers/BUILD.gn
+++ b/build/config/sanitizers/BUILD.gn
@@ -27,6 +27,9 @@ group("deps") {
     deps = [
       ":options_sources",
     ]
+    if (is_mac) {
+      deps += [ ":asan_runtime_stubs" ]
+    }
   }
   if (use_afl) {
     deps += [ "//third_party/afl" ]
@@ -76,12 +79,35 @@ group("deps_no_options") {
 }
 
 if (is_mac && using_sanitizer) {
-  copy("copy_asan_runtime") {
+  action("copy_asan_runtime") {
+    script = "//build/config/sanitizers/copy_asan_runtime.py"
+    _lib_name = "libclang_rt.asan_osx_dynamic.dylib"
     sources = [
-      "$clang_base_path/lib/clang/$clang_version/lib/darwin/libclang_rt.asan_osx_dynamic.dylib",
+      "$clang_base_path/lib/clang/$clang_version/lib/darwin/$_lib_name",
     ]
     outputs = [
-      "$root_out_dir/{{source_file_part}}",
+      "$root_out_dir/$_lib_name",
+    ]
+    args = rebase_path(sources + outputs, root_build_dir)
+  }
+
+  action("generate_asan_runtime_stubs") {
+    script = "//build/config/sanitizers/generate_asan_runtime_stubs.py"
+    inputs = get_target_outputs(":copy_asan_runtime")
+    outputs = [
+      "$target_gen_dir/asan_runtime_stubs.cc",
+    ]
+    args = rebase_path(inputs + outputs, root_build_dir)
+    deps = [ ":copy_asan_runtime" ]
+  }
+
+  source_set("asan_runtime_stubs") {
+    sources = get_target_outputs(":generate_asan_runtime_stubs")
+    deps = [ ":generate_asan_runtime_stubs" ]
+    configs = []
+    cflags = [
+      "-std=c++11",
+      "-mmacosx-version-min=10.7",
     ]
   }
 }
@@ -171,6 +197,10 @@ config("default_sanitizer_ldflags") {
       }
     }
   }
+
+  if (is_mac) {
+    ldflags += [ "-nodefaultlibs", "-lc++", "-lSystem", "-lc++abi" ]
+  }
 }
 
 config("common_sanitizer_flags") {