Fix a snackbar crash about leaking window

chrome/android/java/src/org/chromium/chrome/browser/ChromeActivity.java

 // Copyright 2015 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.chrome.browser;
 
 import android.annotation.SuppressLint;
 import android.annotation.TargetApi;
 import android.app.Activity;
 import android.app.SearchManager;
@@ skipping 686 matching lines @@
             PartnerBrowserCustomizations.setOnInitializeAsyncFinished(new Runnable() {
                 @Override
                 public void run() {
                     if (PartnerBrowserCustomizations.isIncognitoDisabled()) {
                         terminateIncognitoSession();
                     }
                 }
             });
         }
         if (mCompositorViewHolder != null) mCompositorViewHolder.onStart();
+        mSnackbarManager.onStart();
 
         // Explicitly call checkAccessibility() so things are initialized correctly when Chrome has
         // been re-started after closing due to the last tab being closed when homepage is enabled.
         // See crbug.com/541546.
         checkAccessibility();
     }
 
     @Override
     public void onStop() {
         super.onStop();
         if (mContextReporter != null) mContextReporter.disable();
 
         // We want to refresh partner browser provider every onStart().
         mPartnerBrowserRefreshNeeded = true;
         if (mCompositorViewHolder != null) mCompositorViewHolder.onStop();
+        mSnackbarManager.onStop();
     }
 
     @Override
-    public void onPause() {
-        super.onPause();
-        mSnackbarManager.dismissAllSnackbars(false);
-    }
-
-    @Override
     @TargetApi(Build.VERSION_CODES.M)
     public void onProvideAssistContent(AssistContent outContent) {
         if (getAssistStatusHandler() == null || !getAssistStatusHandler().isAssistSupported()) {
             // No information is provided in incognito mode.
             return;
         }
         Tab tab = getActivityTab();
         if (tab != null && !isInOverviewMode()) {
             outContent.setWebUri(Uri.parse(tab.getUrl()));
         }
@@ skipping 869 matching lines @@
     public static int getThemeId() {
         boolean useLowEndTheme =
                 SysUtils.isLowEndDevice() && Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP;
         return (useLowEndTheme ? R.style.MainTheme_LowEnd : R.style.MainTheme);
     }
 
     private void setLowEndTheme() {
         if (getThemeId() == R.style.MainTheme_LowEnd) setTheme(R.style.MainTheme_LowEnd);
     }
 }