[ColorPicker]: Update label of the custom color item

Prefer "Custom color" over "Select color" for consistency. This change
will modify the label for all UIs that use cr-customize-themes, as they
use the same translation string ID.

Bug: 1063856
Change-Id: Ie7edc67f47305071c4971aa9bd13222e9de11a36
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2626227
Commit-Queue: Alex Ilin <alexilin@chromium.org>
Commit-Queue: Tibor Goldschwendt <tiborg@chromium.org>
Auto-Submit: Alex Ilin <alexilin@chromium.org>
Reviewed-by: Tibor Goldschwendt <tiborg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#842797}

chrome/app/generated_resources.grd

@@ -5574,7 +5574,7 @@ Keep your key file in a safe place. You will need it to create new versions of y
         Uninstall
       </message>
       <message name="IDS_NTP_CUSTOMIZE_COLOR_PICKER_LABEL" desc="The label for the color picker in the customization menu on the New Tab Page">
-        Select color
+        Custom color
       </message>
       <message name="IDS_NTP_CUSTOMIZE_DEFAULT_LABEL" desc="The label for the Default theme in the customization menu on the New Tab Page">
         Default

chrome/app/generated_resources_grd/IDS_NTP_CUSTOMIZE_COLOR_PICKER_LABEL.png.sha1

-f73e91018684682237fa39464bb6b467411ac6e5
+25bd90400bbbceaab134f368521d93613c1dae04
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