Fix comment for BrowserNonClientFrameViewBrowserTest.FullscreenForTabTitlebarHeight

The original comment was copy pasted from a different test. This CL fixes
the comment to be more accurate.

Bug: 931031
Change-Id: I3fa298aa60243c618130f7a698705a24507ef98e
Reviewed-on: https://chromium-review.googlesource.com/c/1482251
Auto-Submit: Alan Cutter <alancutter@chromium.org>
Reviewed-by: Bret Sepulveda <bsep@chromium.org>
Commit-Queue: Bret Sepulveda <bsep@chromium.org>
Cr-Commit-Position: refs/heads/master@{#634781}

chrome/browser/ui/views/frame/browser_non_client_frame_view_browsertest.cc

@@ -152,7 +152,8 @@ IN_PROC_BROWSER_TEST_F(SystemWebAppNonClientFrameViewBrowserTest,
                          ->hosted_app_button_container_for_testing());
 }
 
-// Tests the frame color for a bookmark app when a theme is applied.
+// Checks that the title bar for hosted app windows is hidden when in fullscreen
+// for tab mode.
 IN_PROC_BROWSER_TEST_F(BrowserNonClientFrameViewBrowserTest,
                        FullscreenForTabTitlebarHeight) {
   InstallAndLaunchBookmarkApp();