Revert of Remove special theming for CardUnmaskPrompt since it's now automatic...

Revert of Remove special theming for CardUnmaskPrompt since it's now automatic (patchset #2 id:20001 of https://codereview.chromium.org/1096263005/)

Reason for revert:
automatic alert dialog styling was reverted, so revert this as well for now.

Original issue's description:
> Remove special theming for CardUnmaskPrompt since it's now automatic
> for all alert dialogs.
>
> BUG=463576
>
> Committed: https://crrev.com/d9456757bec482f2b27cf75ef7fa2109af0500a6
> Cr-Commit-Position: refs/heads/master@{#326869}

TBR=newt@chromium.org,aurimas@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=463576

Review URL: https://codereview.chromium.org/1097263003

Cr-Commit-Position: refs/heads/master@{#326899}

chrome/android/java/res/values-v17/styles.xml

@@ -4,6 +4,24 @@
      found in the LICENSE file. -->
 
 <resources>
+    <!-- A theme for alert dialogs. The colors are copied from MainTheme, and the window
+         dimensions are copied from *.MinWidth theme variants. Sadly there is no
+         AppCompat.Light.Dialog.Alert or even AppCompat.Light.Dialog.MinWidth. -->
+    <style name="AlertDialogTheme" parent="Theme.AppCompat.Light.Dialog">
+        <item name="android:textColorHighlight">@color/text_highlight_color</item>
+        <item name="android:windowMinWidthMajor">@android:dimen/dialog_min_width_major</item>
+        <item name="android:windowMinWidthMinor">@android:dimen/dialog_min_width_minor</item>
+
+        <!--  Overriding AppCompat values -->
+        <item name="colorAccent">@color/light_active_color</item>
+        <item name="colorControlActivated">@color/light_active_color</item>
+        <item name="colorControlNormal">@color/light_normal_color</item>
+        <item name="colorPrimary">@color/light_active_color</item>
+
+        <!-- Default TintedImageButton tint -->
+        <item name="tint">@color/dark_mode_tint</item>
+    </style>
+
     <!-- Preferences -->
     <style name="PreferencesTheme" parent="ThemeWithActionBar">
         <item name="android:textColorLink">@color/pref_accent_color</item>

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

@@ -12,6 +12,7 @@
     <color name="input_underline_color">#e5e5e5</color>
     <color name="input_underline_error_color">#d32f2f</color>
     <color name="explanation_text_color">#909090</color>
+    <color name="text_highlight_color">#C6DAFC</color>
 
     <!-- Infobar colors -->
     <color name="infobar_background">#fff</color>

chrome/android/java/src/org/chromium/chrome/browser/autofill/CardUnmaskPrompt.java

@@ -116,7 +116,7 @@ public class CardUnmaskPrompt
         mVerificationView = (TextView) v.findViewById(R.id.verification_message);
         ((ImageView) v.findViewById(R.id.cvc_hint_image)).setImageResource(drawableId);
 
-        mDialog = new AlertDialog.Builder(context)
+        mDialog = new AlertDialog.Builder(context, R.style.AlertDialogTheme)
                           .setTitle(title)
                           .setView(v)
                           .setNegativeButton(R.string.cancel, null)