Remove unneeded CustomViewPager class

Originally this hacky class has been introduced by I0824f82c30 to
address bug: 11721001.  Because the bug: 11721001 has been addressed
by I950f13ec40 and etc., this class should be removed.

Bug: 13665882
Change-Id: Iabdd369e4dddb0188534289eea1269fb196895eb

java/res/layout/emoji_palettes_view.xml

@@ -73,7 +73,7 @@
             android:background="@color/emoji_key_background_color"
             android:src="@drawable/sym_keyboard_delete_holo_dark" />
     </LinearLayout>
-    <com.android.inputmethod.keyboard.internal.CustomViewPager
+    <android.support.v4.view.ViewPager
         android:id="@+id/emoji_keyboard_pager"
         android:layout_width="match_parent"
         android:layout_height="wrap_content" />

java/src/com/android/inputmethod/keyboard/EmojiPalettesView.java

@@ -517,6 +517,14 @@ public final class EmojiPalettesView extends LinearLayout implements OnTabChange
         mEmojiLayoutParams.setKeyProperties(spaceKey);
     }
 
+    @Override
+    public boolean dispatchTouchEvent(final MotionEvent ev) {
+        // Add here to the stack trace to nail down the {@link IllegalArgumentException} exception
+        // in MotionEvent that sporadically happens.
+        // TODO: Remove this override method once the issue has been addressed.
+        return super.dispatchTouchEvent(ev);
+    }
+
     @Override
     public void onTabChanged(final String tabId) {
         final int categoryId = mEmojiCategory.getCategoryId(tabId);

java/src/com/android/inputmethod/keyboard/internal/CustomViewPager.java

@@ -1,47 +0,0 @@
-/*
- * Copyright (C) 2013 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package com.android.inputmethod.keyboard.internal;
-
-import android.content.Context;
-import android.support.v4.view.ViewPager;
-import android.util.AttributeSet;
-import android.util.Log;
-import android.view.MotionEvent;
-
-/**
- * Custom view pager to prevent {@link ViewPager} from crashing while handling multi-touch
- * event.
- */
-public class CustomViewPager extends ViewPager {
-    private static final String TAG = CustomViewPager.class.getSimpleName();
-
-    public CustomViewPager(final Context context, final AttributeSet attrs) {
-        super(context, attrs);
-    }
-
-    @Override
-    public boolean onInterceptTouchEvent(final MotionEvent event) {
-        // This only happens when you multi-touch, take the first finger off and move.
-        // Unfortunately this causes {@link ViewPager} to crash, so we will ignore such events.
-        if (event.getAction() == MotionEvent.ACTION_MOVE && event.getPointerId(0) != 0) {
-            Log.w(TAG, "Ignored multi-touch move event to prevent ViewPager from crashing");
-            return false;
-        }
-
-        return super.onInterceptTouchEvent(event);
-    }
-}