[build] symbol_level=1 in simple chrome by default

In simple chrome build, link time of chrome is around 1 minute.
This is due to default symbol_level=2 in simple chrome build.

For faster link time, I will remove symbol_level=2 from simple chrome.
https://chromium-review.googlesource.com/c/chromiumos/chromite/+/1356679

But we want to see stacktrace both on x86 and arm device, so setting symbol_level = 1 in this CL.
symbol_level=1 improves link time of chrome from 61.1s to 34.6s in simple chrome build.

Change-Id: Ie484bc4305d908a0b38fa60c2c57d2a4f7cb3c70
Reviewed-on: https://chromium-review.googlesource.com/c/1358616
Commit-Queue: Takuto Ikuta <tikuta@chromium.org>
Reviewed-by: Dan Erat <derat@chromium.org>
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Reviewed-by: James Cook <jamescook@chromium.org>
Cr-Commit-Position: refs/heads/master@{#613389}

build/config/compiler/compiler.gni

@@ -10,6 +10,10 @@ import("//build/toolchain/goma.gni")
 import("//build/toolchain/toolchain.gni")
 import("//build_overrides/build.gni")
 
+if (is_chromeos) {
+  import("//build/config/chromeos/rules.gni")
+}
+
 if (is_android) {
   import("//build/config/android/abi.gni")
 }
@@ -204,6 +208,11 @@ if (symbol_level == -1) {
     # If you use is_win_fastlink = true or lld or clang then you can set
     # symbol_level = 2 when using goma.
     symbol_level = 1
+  } else if (is_chromeos_chrome) {
+    # Use lower symbol level in Simple Chrome build for faster link time.
+    # For Simple Chrome, this should take precedence over is_official_build,
+    # turned on by --internal.
+    symbol_level = 1
   } else if ((!is_nacl && !is_linux && !is_fuchsia) || is_debug ||
              is_official_build || is_chromecast) {
     # Linux builds slower by having symbols as part of the target binary,