Rework default GN symbol handling for win goma builds.

build/config/compiler/BUILD.gn

 # Copyright (c) 2013 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/config/android/config.gni")
 import("//build/config/chrome_build.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/nacl/config.gni")
 import("//build/toolchain/cc_wrapper.gni")
 import("//build/toolchain/toolchain.gni")
@@ skipping 1460 matching lines @@
 # You can override the symbol level on a per-target basis by removing the
 # default config and then adding the named one you want:
 #
 #   configs -= [ "//build/config/compiler:default_symbols" ]
 #   configs += [ "//build/config/compiler:symbols" ]
 
 # Full symbols.
 config("symbols") {
   if (is_win) {
     import("//build/toolchain/goma.gni")
-    if (use_goma) {
-      # Disable symbols during goma compilation because otherwise the redundant
-      # debug information (repeated in every .obj file) makes linker memory
-      # consumption and link times unsustainable (crbug.com/630074).
-      cflags = []
-    } else {
-      cflags = [ "/Zi" ]  # Produce PDB file, no edit and continue.
-    }
+    assert(!use_goma,
+           "Cannot generate full symbols w/ goma, use symbol_level=1")

[scottmg, 2016/08/03 23:37:24]

Oh, we don't have win_z7 in GN? I guess goma-win is mostly a bot thing by this
point?

+    cflags = [ "/Zi" ]  # Produce PDB file, no edit and continue.
+
     if (is_win_fastlink && visual_studio_version != "2013") {
       # Tell VS 2015+ to create a PDB that references debug
       # information in .obj and .lib files instead of copying
       # it all. This flag is incompatible with /PROFILE
       ldflags = [ "/DEBUG:FASTLINK" ]
     } else {
       ldflags = [ "/DEBUG" ]
     }
   } else {
     if (is_mac || is_ios) {
@@ skipping 63 matching lines @@
 
 if (is_ios || is_mac) {
   # On Mac and iOS, this enables support for ARC (automatic ref-counting).
   # See http://clang.llvm.org/docs/AutomaticReferenceCounting.html.
   config("enable_arc") {
     common_flags = [ "-fobjc-arc" ]
     cflags_objc = common_flags
     cflags_objcc = common_flags
   }
 }