Sign-in dialogs: Use the same font-weight when buttons are focused.

chrome/browser/resources/signin/signin_shared_css.html

Index: chrome/browser/resources/signin/signin_shared_css.html
diff --git a/chrome/browser/resources/signin/signin_shared_css.html b/chrome/browser/resources/signin/signin_shared_css.html
index 5d9037c942a96ef6f05100474ac3a5d0fa047045..a350d032eb819a7327e80487a1d27f0e7baadfe2 100644
--- a/chrome/browser/resources/signin/signin_shared_css.html
+++ b/chrome/browser/resources/signin/signin_shared_css.html
@@ -25,6 +25,7 @@
       paper-button.primary-action {
         --paper-button-flat-keyboard-focus: {
           background: rgb(58, 117, 215);
+          font-weight: 500;
         };
         background: var(--google-blue-500);
         color: white;
@@ -33,6 +34,7 @@
       paper-button.secondary-action {
         --paper-button-flat-keyboard-focus: {
           background: rgba(0, 0, 0, .12);
+          font-weight: 500;
         };
         color: var(--paper-grey-600);
       }