printing_strings: add meaning= for margin settings to fix translation

Currently, Chrome’s print dialog on macOS in German shows the option
“Keine Besuche” (“no visits”) in the margin drop-down, which does not
make any sense and is most likely the translation of “none” in a
different context.

The meaning= properties should make this clear,
for all print margin settings.

R=weili@chromium.org

Skip-Translation-Screenshots-Check: True
Change-Id: Iae824b190fab816a11c7d6e9a7edacba2ac3ce21
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2436739Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#811768}

chrome/app/printing_strings.grdp

@@ -157,16 +157,16 @@
     <message name="IDS_PRINT_PREVIEW_MARGINS_LABEL" desc="Margins option label. Provides user the option to change the margins of the printed page.">
       Margins
     </message>
-    <message name="IDS_PRINT_PREVIEW_DEFAULT_MARGINS" desc="Option that specifies the page be printed with default margins.">
+    <message name="IDS_PRINT_PREVIEW_DEFAULT_MARGINS" desc="Option that specifies the page be printed with default margins." meaning="Default print margins">
       Default
     </message>
-    <message name="IDS_PRINT_PREVIEW_NO_MARGINS" desc="Option that specifies the page be printed with no margins.">
+    <message name="IDS_PRINT_PREVIEW_NO_MARGINS" desc="Option that specifies the page be printed with no margins." meaning="No print margins">
       None
     </message>
-    <message name="IDS_PRINT_PREVIEW_CUSTOM_MARGINS" desc="Option that specifies the page be printed with user-specified custom margins.">
+    <message name="IDS_PRINT_PREVIEW_CUSTOM_MARGINS" desc="Option that specifies the page be printed with user-specified custom margins." meaning="Custom print margins">
       Custom
     </message>
-    <message name="IDS_PRINT_PREVIEW_MINIMUM_MARGINS" desc="Option that specifies the page be printed with the minimum allowed margins by the printer.">
+    <message name="IDS_PRINT_PREVIEW_MINIMUM_MARGINS" desc="Option that specifies the page be printed with the minimum allowed margins by the printer." meaning="Minimum print margins">
       Minimum
     </message>
     <message name="IDS_PRINT_PREVIEW_TOP_MARGIN_LABEL" desc="ARIA label used by screen reader to explain the purpose of the top margin textbox.">