DevTools: Expand grid telemetry to also include grid area settings

Corresponding front-end CL: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/2279485/

Bug: 1100384
Change-Id: Ib0dba6dfed055b6a4987a7182976c07fab8c3ec7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2278853
Commit-Queue: Patrick Brosset <patrick.brosset@microsoft.com>
Reviewed-by: Brandon Goddard <brgoddar@microsoft.com>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#786244}

tools/metrics/histograms/enums.xml

@@ -15930,6 +15930,8 @@ to ensure that the crash string is shown properly on the user-facing crash UI.
   <int value="13" label="showGridGaps.row-gaps"/>
   <int value="14" label="showGridGaps.column-gaps"/>
   <int value="15" label="showGridGaps.both"/>
+  <int value="16" label="showGridAreas.false"/>
+  <int value="17" label="showGridAreas.true"/>
 </enum>
 
 <enum name="DevToolsIssuesPanelOpenedFrom">