win: Enable -Wexit-time-destructors for content/.

After this, for all targets where the warning is enabled on non-Win, it's now
enabled on Windows too.

Bug: 404525
Change-Id: I2518fe482e04ba3c4b9964c49ee3fc3c4217d170
Reviewed-on: https://chromium-review.googlesource.com/1231838
Reviewed-by: Antoine Labour <piman@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#592230}

content/BUILD.gn

@@ -9,11 +9,10 @@ import("//ppapi/buildflags/buildflags.gni")
 # Applied by targets internal to content.
 config("content_implementation") {
   defines = [ "CONTENT_IMPLEMENTATION" ]
-  configs = [ "//build/config/compiler:noshadowing" ]
-  if (!is_win) {
-    # TODO(thakis): Enable on Windows too, http://crbug.com/404525
-    configs += [ "//build/config/compiler:wexit_time_destructors" ]
-  }
+  configs = [
+    "//build/config/compiler:noshadowing",
+    "//build/config/compiler:wexit_time_destructors",
+  ]
 }
 
 # When targets depend on, e.g. //content/public/browser, what happens? To