Remove -Wno-address-of-packed-member from default_warnings

This is just for command line flag clean up.

Bug: 619640
Change-Id: Ie0611e6ff15db10721a55c29e0665be1c4295561
Reviewed-on: https://chromium-review.googlesource.com/1154227
Commit-Queue: Takuto Ikuta <tikuta@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Reviewed-by: Hans Wennborg <hans@chromium.org>
Cr-Commit-Position: refs/heads/master@{#579023}

build/config/compiler/BUILD.gn

@@ -1441,9 +1441,6 @@ config("default_warnings") {
       cflags += [
         # TODO(thakis): https://crbug.com/604888
         "-Wno-undefined-var-template",
-
-        # TODO(hans): https://crbug.com/637306
-        "-Wno-address-of-packed-member",
       ]
       if (current_toolchain == host_toolchain || !use_xcode_clang ||
           xcode_version_int >= 930) {

chrome/utility/safe_browsing/mac/BUILD.gn

@@ -46,6 +46,11 @@ source_set("dmg_common") {
     "//third_party/zlib",
   ]
 
+  cflags = [
+    # For HFSPlusForkData and HFSPlusVolumeHeader (crbug.com/619640).
+    "-Wno-address-of-packed-member",
+  ]
+
   public_configs = [ ":dmg_public_config" ]
 }