Trivial: fixing and clarifying comments in language detection unit test.

R=meredithl

Change-Id: Iacf878aea64518ad9e66a661589c7e11f55cc66e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2362382Reviewed-by: Meredith Lane <meredithl@chromium.org>
Commit-Queue: Chris Hall <chrishall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#799895}

ui/accessibility/ax_language_detection_unittest.cc

@@ -842,6 +842,7 @@ TEST_F(AXLanguageDetectionTestStaticContent, kLanguageUntouched) {
 
 // Test RegisterLanguageDetectionObserver correctly respects the feature flag.
 TEST_F(AXLanguageDetectionTestFixture, ObserverRegistrationObeysFlag) {
+  // Enable only the flag controlling static language detection.
   base::CommandLine::ForCurrentProcess()->AppendSwitch(
       ::switches::kEnableExperimentalAccessibilityLanguageDetection);
 
@@ -855,11 +856,12 @@ TEST_F(AXLanguageDetectionTestFixture, ObserverRegistrationObeysFlag) {
 
   ASSERT_EQ(getObserver(tree), nullptr);
 
+  // Now enable the dynamic feature flag.
   base::CommandLine::ForCurrentProcess()->AppendSwitch(
       ::switches::kEnableExperimentalAccessibilityLanguageDetectionDynamic);
 
-  // Try registration without turning on Dynamic feature flag, this should
-  // do nothing.
+  // Try registration again, this should construct and register observer as flag
+  // is now enabled.
   tree.language_detection_manager->RegisterLanguageDetectionObserver();
 
   // Check our observer was constructed.