Update text style of borderless button in signin promo card

Google sans is commonly used in button texts and headlines. For style
consistency across the clank, this CL updates the font style of the
button from Roboto to Google sans.

Bug: 1053602
Change-Id: I189a968487ae89a5c27f1b25ca426143de3a8e95
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2063415Reviewed-by: Boris Sazonov <bsazonov@chromium.org>
Reviewed-by: Theresa  <twellington@chromium.org>
Commit-Queue: Lijin Shen <lazzzis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#743158}

chrome/android/java/res/values/styles.xml

@@ -581,7 +581,6 @@
     <style name="SigninButtonBorderlessRegular" parent="@style/TextButton">
         <item name="android:paddingStart">0dp</item>
         <item name="android:paddingEnd">0dp</item>
-        <item name="android:textAppearance">@style/TextAppearance.TextMedium.Blue</item>
     </style>
     <style name="NavigationPopupDialog" parent="Widget.AppCompat.Light.ListPopupWindow" />
 

chrome/test/data/android/render_tests/ArticleSnippetsTest.NightModeDisabled-hot_state_personalized_signin_promo.Nexus_5-19.png.sha1

-cd127efdb08111be0465f3295ab31cbecc212c3a
\ No newline at end of file
+c37f218483916934aa2b427d90d44767fd7e93fd
\ No newline at end of file

chrome/test/data/android/render_tests/ArticleSnippetsTest.NightModeDisabled-hot_state_personalized_signin_promo.Nexus_5X-23.png.sha1

-81ea853a59e70be29e776c25ffa325d4ce657805
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+8ba877f0f0f840971d3b501ce170825f03b90a01
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chrome/test/data/android/render_tests/ArticleSnippetsTest.NightModeEnabled-hot_state_personalized_signin_promo.Nexus_5-19.png.sha1

-724ea7b467165f03bc2f5c9ec92b1c6c6d9d5dac
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+ffb3888992096cfebcce0d33528a20297b185f21
\ No newline at end of file

chrome/test/data/android/render_tests/ArticleSnippetsTest.NightModeEnabled-hot_state_personalized_signin_promo.Nexus_5X-23.png.sha1

-28a4e8d27af8df0715f6855d295017418368ab8e
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+12c0edd512e158d558de9fe94e3fac5cfa300a6b
\ No newline at end of file