Add a UMA counter for tap disambiguation result.

content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.content.browser;
 
 import android.annotation.SuppressLint;
 import android.annotation.TargetApi;
 import android.app.assist.AssistStructure.ViewNode;
 import android.content.ClipData;
@@ skipping 1356 matching lines @@
             }
         }
         if (mNativeContentViewCore != 0) nativeSetFocus(mNativeContentViewCore, gainFocus);
     }
 
     /**
      * @see View#onKeyUp(int, KeyEvent)
      */
     public boolean onKeyUp(int keyCode, KeyEvent event) {
         if (mPopupZoomer.isShowing() && keyCode == KeyEvent.KEYCODE_BACK) {
-            mPopupZoomer.hide(true);
+            mPopupZoomer.backButtonPressed();
             return true;
         }
         return mContainerViewInternals.super_onKeyUp(keyCode, event);
     }
 
     /**
      * @see View#dispatchKeyEvent(KeyEvent)
      */
     public boolean dispatchKeyEvent(KeyEvent event) {
         if (GamepadList.dispatchKeyEvent(event)) return true;
@@ skipping 1309 matching lines @@
     private native void nativeSetTextTrackSettings(long nativeContentViewCoreImpl,
             boolean textTracksEnabled, String textTrackBackgroundColor, String textTrackFontFamily,
             String textTrackFontStyle, String textTrackFontVariant, String textTrackTextColor,
             String textTrackTextShadow, String textTrackTextSize);
 
     private native void nativeSetBackgroundOpaque(long nativeContentViewCoreImpl, boolean opaque);
     private native boolean nativeIsTouchDragDropEnabled(long nativeContentViewCoreImpl);
     private native void nativeOnDragEvent(long nativeContentViewCoreImpl, int action, int x, int y,
             int screenX, int screenY, String[] mimeTypes, String content);
 }