Remove special theming for CardUnmaskPrompt since it's now automatic

for all alert dialogs.

BUG=463576

Review URL: https://codereview.chromium.org/1096263005

Cr-Commit-Position: refs/heads/master@{#326869}

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

@@ -4,24 +4,6 @@
      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

@@ -12,7 +12,6 @@
     <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, R.style.AlertDialogTheme)
+        mDialog = new AlertDialog.Builder(context)
                           .setTitle(title)
                           .setView(v)
                           .setNegativeButton(R.string.cancel, null)