Download home: Change "Just Now" to "Just now".

The UI string should be sentense case. So "Scheduled for later" section
header and "Just now" section header can match.

Bug: 1078454
Change-Id: Iedf457c3dd60da07b29b559d2e5082b0b35bd5a4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2256742Reviewed-by: Shakti Sahu <shaktisahu@chromium.org>
Commit-Queue: Xing Liu <xingliu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#780859}

chrome/browser/ui/android/strings/android_chrome_strings.grd

@@ -2117,7 +2117,7 @@ To change this setting, <ph name="BEGIN_LINK">&lt;resetlink&gt;</ph>reset sync<p
         <ph name="FILE_SIZE_OF_TOTAL">%1$s<ex>1.56 MB / 10MB</ex></ph> <ph name="SEPARATOR">•</ph> <ph name="DESCRIPTION">%2$s<ex>failed</ex></ph>
       </message>
       <message name="IDS_DOWNLOAD_MANAGER_JUST_NOW" desc="Text on a label describing that the associated download event happened just now.">
-        Just Now
+        Just now
       </message>
       <message name="IDS_DOWNLOAD_MANAGER_SCHEDULED_LATER" desc="Text on a label describing that the associated download is scheduled to start later.">
         Scheduled for later