[TaskEnvironment] Add plural to ValidTraits

Found while writing docs that this was grammatically incorrect and
inconsistent with other "ValidTraits" around.

TBR=fdoray@chromium.org
(for side-effects outside //base)

Bug: 1002654
Change-Id: Ia8974f79d91021cc258775cdf57b18fe2edc9800
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1795990
Commit-Queue: Gabriel Charette <gab@chromium.org>
Auto-Submit: Gabriel Charette <gab@chromium.org>
Reviewed-by: François Doray <fdoray@chromium.org>
Cr-Commit-Position: refs/heads/master@{#695619}

base/test/task_environment.h

@@ -152,19 +152,19 @@ class TaskEnvironment {
   };
 
   // List of traits that are valid inputs for the constructor below.
-  struct ValidTrait {
-    ValidTrait(TimeSource);
-    ValidTrait(MainThreadType);
-    ValidTrait(ThreadPoolExecutionMode);
-    ValidTrait(SubclassCreatesDefaultTaskRunner);
-    ValidTrait(ThreadingMode);
+  struct ValidTraits {
+    ValidTraits(TimeSource);
+    ValidTraits(MainThreadType);
+    ValidTraits(ThreadPoolExecutionMode);
+    ValidTraits(SubclassCreatesDefaultTaskRunner);
+    ValidTraits(ThreadingMode);
   };
 
   // Constructor accepts zero or more traits which customize the testing
   // environment.
   template <typename... TaskEnvironmentTraits,
             class CheckArgumentsAreValid = std::enable_if_t<
-                trait_helpers::AreValidTraits<ValidTrait,
+                trait_helpers::AreValidTraits<ValidTraits,
                                               TaskEnvironmentTraits...>::value>>
   NOINLINE explicit TaskEnvironment(TaskEnvironmentTraits... traits)
       : TaskEnvironment(

chrome/test/base/browser_with_test_window_test.h

@@ -81,7 +81,7 @@ class BrowserWithTestWindowTest : public testing::Test {
 
     // TODO(alexclarke): Make content::BrowserTaskEnvironment::ValidTraits
     // imply this.
-    explicit ValidTraits(base::test::TaskEnvironment::ValidTrait);
+    explicit ValidTraits(base::test::TaskEnvironment::ValidTraits);
   };
 
   // Creates a BrowserWithTestWindowTest with zero or more traits. By default

content/public/test/browser_task_environment.h

@@ -142,7 +142,7 @@ class BrowserTaskEnvironment : public base::test::TaskEnvironment {
   static constexpr MainThreadType IO_MAINLOOP = MainThreadType::IO;
 
   struct ValidTraits {
-    ValidTraits(TaskEnvironment::ValidTrait);
+    ValidTraits(TaskEnvironment::ValidTraits);
     ValidTraits(Options);
   };