MD Settings: create a global "action button" style (blue, flat)

chrome/browser/resources/settings/settings_shared_css.html

Index: chrome/browser/resources/settings/settings_shared_css.html
diff --git a/chrome/browser/resources/settings/settings_shared_css.html b/chrome/browser/resources/settings/settings_shared_css.html
index b39dc83041ccb70375f44afbef72305fad1d08f2..f9cf3280aea96af486076b53942f916f5991f3fe 100644
--- a/chrome/browser/resources/settings/settings_shared_css.html
+++ b/chrome/browser/resources/settings/settings_shared_css.html
@@ -40,6 +40,16 @@
         min-width: auto;
       }
 
+      paper-button.call-to-action {

[dpapad, 2016/03/01 02:18:03]

Can we keep the "action-button" name? Seems much more intuitive than the
proposed naming
1) makes it clear that it refers to a button.
2) Sounds like a CSS class name (unlike new naming which without context I would
have never guessed it is a CSS class name)

[Dan Beam, 2016/03/01 17:44:04]

Done. (though for future reference, I don't agree with either of your points I
just don't care -- <button> is also a tag [which this is not], there was already
a "paper-button" in the selector so you know it only affects those things, and
there's no "sounds like a class name" unless you mean presentational -- which is
a bad idea. with these ideas combined we end up with bad class names like
.red-div which are brittle and too specific.  I also thought about .important or
.recommended [which is what Alan said these buttons are in some cases, like
"Sign in"], but it didn't always match)

[dpapad, 2016/03/01 17:56:11]

For future reference, I think is better if we discuss about things we don't
agree about, instead of doing them and then adding a huge "I don't agree with
this." note. I have found myself doing the same in previous CLs, and I don't
think it is helping us in the long run.

Regarding the "-button" suffix, I am fine with just "action" as the CSS class
name, dropping the suffix completely. call-for-action sounded weird to me (and
still does), but because we never had the discussion (the one I am referring in
previous paragraph) I was never exposed to your thinking of choosing that name.

+        background: var(--google-blue-500);
+        color: white;
+        font-weight: 500;
+      }
+
+      paper-button.call-to-action[disabled] {
+        opacity: .25;  /* TODO(dbeam): check this value with bettes. */
+      }
+
       paper-button[toggles][active] {
         background-color: var(--paper-grey-300);
       }