[Android][WebSignin][UI] Add visial feedback when entry is selected

This CL adds visual feedback when an entry is selected in the expanded
account list.

(cherry picked from commit 790c32c397ee5aa960a8bab673045be3838a60a0)

Bug: 1135141
Change-Id: Idba767ae72a7e9d258a35cf3df1440e6cf35c076
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2449989
Reviewed-by: Boris Sazonov <[email protected]>
Commit-Queue: Alice Wang <[email protected]>
Cr-Original-Commit-Position: refs/heads/master@{#814177}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2455709
Reviewed-by: Alice Wang <[email protected]>
Cr-Commit-Position: refs/branch-heads/4280@{#70}
Cr-Branched-From: ea420fb963f9658c9969b6513c56b8f47efa1a2a-refs/heads/master@{#812852}
diff --git a/chrome/android/java/res/layout/account_picker_incognito_row.xml b/chrome/android/java/res/layout/account_picker_incognito_row.xml
index 334557fa..b7a41fa7 100644
--- a/chrome/android/java/res/layout/account_picker_incognito_row.xml
+++ b/chrome/android/java/res/layout/account_picker_incognito_row.xml
@@ -8,6 +8,7 @@
     xmlns:app="http://schemas.android.com/apk/res-auto"
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
+    android:background="?attr/selectableItemBackground"
     android:drawablePadding="24dp"
     android:paddingStart="16dp"
     android:paddingEnd="8dp"
diff --git a/chrome/android/java/res/layout/account_picker_new_account_row.xml b/chrome/android/java/res/layout/account_picker_new_account_row.xml
index a79e61e..c284359 100644
--- a/chrome/android/java/res/layout/account_picker_new_account_row.xml
+++ b/chrome/android/java/res/layout/account_picker_new_account_row.xml
@@ -8,6 +8,7 @@
     xmlns:app="http://schemas.android.com/apk/res-auto"
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
+    android:background="?attr/selectableItemBackground"
     android:drawablePadding="16dp"
     android:paddingStart="8dp"
     android:paddingEnd="8dp"
diff --git a/chrome/android/java/res/layout/account_picker_row.xml b/chrome/android/java/res/layout/account_picker_row.xml
index efa1d3a..430df92 100644
--- a/chrome/android/java/res/layout/account_picker_row.xml
+++ b/chrome/android/java/res/layout/account_picker_row.xml
@@ -6,6 +6,7 @@
     xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
+    android:background="?attr/selectableItemBackground"
     android:gravity="center_vertical"
     android:orientation="horizontal"
     android:padding="8dp">