Rework default GN symbol handling for win goma builds.

build/config/compiler/compiler.gni

Index: build/config/compiler/compiler.gni
diff --git a/build/config/compiler/compiler.gni b/build/config/compiler/compiler.gni
index 2e5072e2589133090ed96f857b216186ee3a6836..46db08fefb6d81dc4582f61aac6585da8a723bbc 100644
--- a/build/config/compiler/compiler.gni
+++ b/build/config/compiler/compiler.gni
@@ -82,6 +82,16 @@ 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) {

[Nico, 2016/08/22 16:14:28]

like rnk says, this should probably grow a !is_clang too

+    # goma doesn't support PDB files, so we 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).
+    symbol_level = 1
+  } else if (is_win && is_clang && !using_sanitizer) {
+    # TODO(thakis): Remove this again once building with clang/win and
+    # debug info doesn't make link.exe run for hours.

[Nico, 2016/08/22 16:14:28]

(i removed this a while ago, please don't accidentally add it back in this cl)

+    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,