Revert to using system AlertDialog.Builder.

Due to b/20882793 bug in AppCompat we need to use system AlertDialog.Builder
for all the dialogs that contain EditText.

BUG=484658

Review URL: https://codereview.chromium.org/1128683004

Cr-Commit-Position: refs/heads/master@{#329688}

chrome/android/java/res/layout/add_to_homescreen_dialog.xml

@@ -18,7 +18,8 @@
         android:layout_width="32dp"
         android:layout_height="32dp"
         android:layout_marginTop="10dp" />
-    <EditText android:id="@+id/text"
+    <org.chromium.chrome.browser.widget.AlertDialogEditText
+        android:id="@+id/text"
         android:inputType="text"
         android:layout_width="match_parent"
         android:layout_height="32dp"

chrome/android/java/src/org/chromium/chrome/browser/webapps/AddToHomescreenDialog.java

@@ -5,9 +5,9 @@
 package org.chromium.chrome.browser.webapps;
 
 import android.app.Activity;
+import android.app.AlertDialog;
 import android.content.DialogInterface;
 import android.graphics.Bitmap;
-import android.support.v7.app.AlertDialog;
 import android.text.Editable;
 import android.text.TextUtils;
 import android.text.TextWatcher;
@@ -40,7 +40,7 @@ public class AddToHomescreenDialog {
     public static void show(final Activity activity, final Tab currentTab) {
         View view = activity.getLayoutInflater().inflate(
                 R.layout.add_to_homescreen_dialog, null);
-        AlertDialog.Builder builder = new AlertDialog.Builder(activity, R.style.AlertDialogTheme)
+        AlertDialog.Builder builder = new AlertDialog.Builder(activity)
                 .setTitle(R.string.menu_add_to_homescreen)
                 .setNegativeButton(R.string.cancel,
                         new DialogInterface.OnClickListener() {
@@ -54,7 +54,7 @@ public class AddToHomescreenDialog {
         // On click of the menu item for "add to homescreen", an alert dialog pops asking the user
         // if the title needs to be edited. On click of "Add", shortcut is created. Default
         // title is the title of the page. OK button is disabled if the title text is empty.
-        final View progressBarView = (View) view.findViewById(R.id.spinny);
+        final View progressBarView = view.findViewById(R.id.spinny);
         final ImageView iconView = (ImageView) view.findViewById(R.id.icon);
         final EditText input = (EditText) view.findViewById(R.id.text);
         input.setEnabled(false);

chrome/android/javatests_shell/src/org/chromium/chrome/browser/webapps/AddToHomescreenDialogTest.java

@@ -4,8 +4,8 @@
 
 package org.chromium.chrome.browser.webapps;
 
+import android.app.AlertDialog;
 import android.content.DialogInterface;
-import android.support.v7.app.AlertDialog;
 import android.test.suitebuilder.annotation.SmallTest;
 
 import org.chromium.base.ThreadUtils;