Style the extensions virtual keyboard

ui/keyboard/resources/elements/kb-key.html

Index: ui/keyboard/resources/elements/kb-key.html
diff --git a/ui/keyboard/resources/elements/kb-key.html b/ui/keyboard/resources/elements/kb-key.html
index c0d2556446faccc4022460c307126adb037cfc31..7226b69441a8e833a4c9f1f511fafb5a1391b885 100644
--- a/ui/keyboard/resources/elements/kb-key.html
+++ b/ui/keyboard/resources/elements/kb-key.html
@@ -26,7 +26,8 @@
         position: absolute;
         right: 0;
         top: 0;
-        text-align: center;
+        padding-left: 14px;
+        padding-right: 14px;

[bshe, 2013/06/20 19:41:51]

Not sure why do we need padding here. It should already center aligned
(inherited from kb-row)? I worry this may look bad when keyboard scale (with
absolute pixel value). 

[SteveT, 2013/06/20 20:58:33]

Centred text will remain the same. This padding ensures that text aligned on the
left or right will have some padding to keep it looking good within the key
bounds.

Yes, it's true that scaling the keys does not scale this padding well, but 14px
looks fine at most large-screen resolutions, so I think this is OK until we
discuss how to fix the bigger issue of flex-box padding.

       }
     </style>
     <div id="key" class="key">