Re-land "Rework default GN symbol handling for win goma builds."

This relands r415325 with the neede fix.

TBR=thakis@chromium.org
BUG=634184

Review-Url: https://codereview.chromium.org/2296953002
Cr-Commit-Position: refs/heads/master@{#415435}

build/config/compiler/BUILD.gn

@@ -1505,14 +1505,8 @@ config("default_optimization") {
 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.
-    }
+    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

build/config/compiler/compiler.gni

@@ -6,6 +6,7 @@ import("//build/config/android/config.gni")
 import("//build/config/chrome_build.gni")
 import("//build/config/chromecast_build.gni")
 import("//build/config/sanitizers/sanitizers.gni")
+import("//build/toolchain/goma.gni")
 import("//build/toolchain/toolchain.gni")
 
 declare_args() {
@@ -82,6 +83,13 @@ if (symbol_level == -1) {
     # With instrumentation enabled, debug info puts libchrome.so over 4gb, which
     # causes the linker to produce an invalid ELF. http://crbug.com/574476
     symbol_level = 0
+  } else if (is_win && use_goma && !is_clang) {
+    # goma doesn't support PDB files, so we disable symbols during goma
+    # compilation because otherwise the redundant debug information generated
+    # by visual studio (repeated in every .obj file) makes linker
+    # memory consumption and link times unsustainable (crbug.com/630074).
+    # Clang on windows does not have this issue.
+    symbol_level = 1
   } else if (!is_linux || is_debug || is_official_build || is_chromecast) {
     # Linux is slowed by having symbols as part of the target binary, whereas
     # Mac and Windows have them separate, so in Release Linux, default them off,