Update close button strings for incognito and guest menus.

This CL capitalizes the letters for Guest and Incognito in the chip menu
to follow the guide in go/chromewords.

Screenshot:
https://screenshot.googleplex.com/AcFJbt6g6skM2oY.png

Bug: 1105763
Change-Id: I208f3b9f7ab9150b33d84d60b76342b1199a830c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2421667
Commit-Queue: Mariam Ali <alimariam@google.com>
Reviewed-by: Ramin Halavati <rhalavati@chromium.org>
Cr-Commit-Position: refs/heads/master@{#809767}

chrome/app/generated_resources.grd

@@ -10682,7 +10682,7 @@ Please help our engineers fix this problem. Tell us what happened right before y
       Exit Incognito
     </message>
     <message name="IDS_INCOGNITO_PROFILE_MENU_CLOSE_BUTTON_NEW" desc="The text of the button offering to close all incognito windows.">
-      Close incognito
+      Close Incognito
     </message>
 
    <!-- Guest Profile Menu bubble. -->
@@ -10692,10 +10692,10 @@ Please help our engineers fix this problem. Tell us what happened right before y
         other {# open windows}
       }
     </message>
-    <message name="IDS_GUEST_PROFILE_MENU_CLOSE_BUTTON" desc="The text of the button offering to close all guest windows.">
+    <message name="IDS_GUEST_PROFILE_MENU_CLOSE_BUTTON" desc="The text of the button offering to close all guest windows. The number in ICU syntax represents the number of open guest windows, but it is not used in the English text and can be used to choose singular/plural in translation to other languages, if needed.[ICU Syntax]">
       {0, plural,
-        =1 {Close guest}
-        other {Close guest}
+        =1 {Close Guest}
+        other {Close Guest}
       }
     </message>
 

chrome/app/generated_resources_grd/IDS_GUEST_PROFILE_MENU_CLOSE_BUTTON.png.sha1

-d5e17649bc7e9f520e5b682e04146df8a2e1e5c4
+3499540316dd284fdafc7e51eca3f422c326da2d
\ No newline at end of file

chrome/app/generated_resources_grd/IDS_INCOGNITO_PROFILE_MENU_CLOSE_BUTTON_NEW.png.sha1

-2baf2a11aadf5ce9d562f1417ee7d3ab2c404779
+6bb00a404baf88687babf5a74b01a0802ba7bd52
\ No newline at end of file