Reland "Add gtest absl deps to the absl component."

This is a reland of 3a2a481f

This CL moves the declare_arg of gtest_enable_absl_printers to
//build_overrides (which is already imported by googletest and
abseil-cpp BUILD.gn files) in order to avoid the "undefined identifier"
error when build_with_chromium=true.

Original change's description:
> Add gtest absl deps to the absl component.
>
> This CL conditionally adds absl/debugging deps to the absl component
> if build_with_chromium=false. This will allow downstream projects to
> use gtest with absl (for pretty printers and matchers) but it will
> remove these dependencies in Chromium to avoid to add static
> initializers.
>
> When static initializers will be removed, the dependency will not be
> conditional so Chromium will also be able to set
> 'gtest_enable_absl_printers=true'.
>
> Bug: 1046390
> Change-Id: Ifffea81ba8f7a9412bebc3798e8f79eaff2777d7
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2262972
> Commit-Queue: Mirko Bonadei <mbonadei@chromium.org>
> Auto-Submit: Mirko Bonadei <mbonadei@chromium.org>
> Reviewed-by: Nico Weber <thakis@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#782889}

Bug: 1046390
Change-Id: Id977a6a868b389b4d9924eb3af5a5f5cd0c3f4ee
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2270298
Auto-Submit: Mirko Bonadei <mbonadei@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#783087}

build_overrides/build.gni

@@ -26,6 +26,10 @@ declare_args() {
   # no-op to set up trybot infrastructure.
   # TODO(crbug/1006769): Switch to perfetto's client library.
   use_perfetto_client_library = false
+
+  # If true, it assumes that //third_party/abseil-cpp is an available
+  # dependency for googletest.
+  gtest_enable_absl_printers = false
 }
 
 # Allows different projects to specify their own suppressions and blacklist

third_party/abseil-cpp/BUILD.gn

@@ -7,6 +7,7 @@
 # without these options will be part of the same program.
 
 import("//build/toolchain/toolchain.gni")
+import("//build_overrides/build.gni")
 import("//testing/test.gni")
 
 config("absl_component_build") {
@@ -62,6 +63,17 @@ component("absl") {
     "//third_party/abseil-cpp/absl/types:optional",
     "//third_party/abseil-cpp/absl/types:variant",
   ]
+  if (!build_with_chromium && gtest_enable_absl_printers) {
+    # The following dependencies contain static initializers which are
+    # banned by Chromium. They are needed by gtest when the GN arg
+    # gtest_enable_absl_printers is set to true (this is never done by
+    # Chromium).
+    public_deps += [
+        "//third_party/abseil-cpp/absl/debugging:failure_signal_handler",
+        "//third_party/abseil-cpp/absl/debugging:stacktrace",
+        "//third_party/abseil-cpp/absl/debugging:symbolize",
+    ]
+  }
 }
 
 group("default") {

third_party/googletest/BUILD.gn

@@ -4,11 +4,6 @@
 
 import("//build_overrides/build.gni")
 
-declare_args() {
-  # If true, it assumes that //third_party/abseil-cpp is an available dependency.
-  gtest_enable_absl_printers = false
-}
-
 config("gtest_config") {
   visibility = [ ":*" ]  # gmock also shares this config.