[Mac] Added Comments to TextSuggestionsTouchBarController Tests

Some TextSuggestionsTouchBarController unit tests were missing
comments. Comments were added where necessary.

Bug: 717553
Change-Id: I5e41114a5618899bba61d4867d17634ab151fcfc
Reviewed-on: https://chromium-review.googlesource.com/1178575Reviewed-by: Sarah Chan <spqchan@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Commit-Queue: Avi Drissman <avi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#583886}

chrome/browser/ui/cocoa/touchbar/text_suggestions_touch_bar_controller.mm

@@ -243,7 +243,6 @@ class WebContentsTextObserver : public content::WebContentsObserver {
                           suggestions_.reset([candidates copy]);
                           [controller_ invalidateTouchBar];
                         });
-
                       }];
 }
 

chrome/browser/ui/cocoa/touchbar/text_suggestions_touch_bar_controller_unittest.mm

@@ -35,6 +35,7 @@ class TextSuggestionsTouchBarControllerTest : public CocoaTest {
   base::scoped_nsobject<TextSuggestionsTouchBarController> controller_;
 };
 
+// Tests that the NSCandidateListTouchBarItem collapses properly.
 TEST_F(TextSuggestionsTouchBarControllerTest, CollapsedCandidateList) {
   if (@available(macOS 10.12.2, *)) {
     base::scoped_nsobject<NSCandidateListTouchBarItem> item;
@@ -133,6 +134,7 @@ TEST_F(TextSuggestionsTouchBarControllerTest, MultipleWordsEditingWordRange) {
   EXPECT_EQ(gfx::Range(6, 11), GetEditingWordRange(kMultipleWords, 11));
 }
 
+// Tests that touch bar usage is properly logged.
 TEST_F(TextSuggestionsTouchBarControllerTest, TouchBarMetrics) {
   if (@available(macOS 10.12.2, *)) {
     base::HistogramTester histogram_tester;