Allow non-component debug builds for projects other than Chromium.

This compiler config is used by other projects, and at least WebRTC
is not switching to component builds.

`build_with_chromium` variable is supposed to be true only when
the current root project is Chromium, so do the check only then.

Bug: 945515
Change-Id: I37076a8724a0b9a067b20dec9186d551e41fc898
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1543251Reviewed-by: Jochen Eisinger <jochen@chromium.org>
Reviewed-by: Sylvain Defresne <sdefresne@chromium.org>
Commit-Queue: Oleh Prypin <oprypin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#645293}

build/config/compiler/compiler.gni

@@ -259,9 +259,11 @@ if (symbol_level == -1) {
 # because the is_component_build flag is set to false in various components of
 # the build (like nacl) and we don't want to assert on those.
 # iOS does not support component builds so add an exception for this platform.
-assert(symbol_level != 2 || current_toolchain != default_toolchain ||
-           is_component_build || !is_debug || is_ios,
-       "Can't do non-component debug builds at symbol_level=2")
+if (build_with_chromium) {
+  assert(symbol_level != 2 || current_toolchain != default_toolchain ||
+             is_component_build || !is_debug || is_ios,
+         "Can't do non-component debug builds at symbol_level=2")
+}
 
 # Assert that the configuration isn't going to hit https://crbug.com/648948.
 # An exception is made when target_os == "chromeos" as we only use the Android