[Suggestions UI] Drop Bitmap references from articles under memory pressure.

chrome/android/javatests/src/org/chromium/chrome/browser/ntp/snippets/ArticleSnippetsTest.java

 // Copyright 2016 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.ntp.snippets;
 
+import android.graphics.Bitmap;
 import android.graphics.BitmapFactory;
 import android.support.test.InstrumentationRegistry;
 import android.support.test.filters.MediumTest;
 import android.util.TypedValue;
 import android.view.ViewGroup;
 import android.widget.FrameLayout;
 
 import org.junit.Before;
 import org.junit.Rule;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 
+import org.chromium.base.DiscardableReferencePool;
 import org.chromium.base.ThreadUtils;
 import org.chromium.base.test.util.CommandLineFlags;
 import org.chromium.base.test.util.Feature;
 import org.chromium.base.test.util.RetryOnFailure;
 import org.chromium.chrome.R;
 import org.chromium.chrome.browser.ChromeActivity;
 import org.chromium.chrome.browser.ChromeSwitches;
 import org.chromium.chrome.browser.favicon.FaviconHelper.FaviconImageCallback;
 import org.chromium.chrome.browser.favicon.FaviconHelper.IconAvailabilityCallback;
 import org.chromium.chrome.browser.favicon.LargeIconBridge.LargeIconCallback;
@@ skipping 110 matching lines @@
     private void setupTestData() {
         @CategoryInt
         int fullCategory = 0;
         @CategoryInt
         int minimalCategory = 1;
         SnippetArticle shortSnippet = new SnippetArticle(fullCategory, "id1", "Snippet",
                 "Publisher", "Preview Text", "www.google.com",
                 1466614774, // Publish timestamp
                 10f, // Score
                 1466634774); // Fetch timestamp
-        shortSnippet.setThumbnailBitmap(
+
+        Bitmap thumbnail =
                 BitmapFactory.decodeResource(mActivityTestRule.getActivity().getResources(),
-                        R.drawable.signin_promo_illustration));
+                        R.drawable.signin_promo_illustration);
+        shortSnippet.setThumbnailBitmap(mUiDelegate.getReferencePool().put(thumbnail));
 
         SnippetArticle longSnippet = new SnippetArticle(fullCategory, "id2",
                 new String(new char[20]).replace("\0", "Snippet "),
                 new String(new char[20]).replace("\0", "Publisher "),
                 new String(new char[80]).replace("\0", "Preview Text "), "www.google.com",
                 1466614074, // Publish timestamp
                 20f, // Score
                 1466634774); // Fetch timestamp
 
         SnippetArticle minimalSnippet = new SnippetArticle(minimalCategory, "id3",
@@ skipping 37 matching lines @@
         mSnippetsSource = new FakeSuggestionsSource();
     }
 
     /**
      * A SuggestionsUiDelegate to initialize our Adapter.
      */
     private class MockUiDelegate implements SuggestionsUiDelegate {
         private SuggestionsEventReporter mSuggestionsEventReporter =
                 new DummySuggestionsEventReporter();
         private SuggestionsRanker mSuggestionsRanker = new SuggestionsRanker();
+        private final DiscardableReferencePool mReferencePool = new DiscardableReferencePool();
 
         @Override
         public void getLocalFaviconImageForURL(
                 final String url, int size, final FaviconImageCallback faviconCallback) {
             // Run the callback asynchronously incase the caller made that assumption.
             ThreadUtils.postOnUiThread(new Runnable(){
                 @Override
                 public void run() {
                     // Return an arbitrary drawable.
                     faviconCallback.onFaviconAvailable(
@@ skipping 20 matching lines @@
         public SuggestionsSource getSuggestionsSource() {
             return mSnippetsSource;
         }
 
         @Override
         public SuggestionsRanker getSuggestionsRanker() {
             return mSuggestionsRanker;
         }
 
         @Override
+        public DiscardableReferencePool getReferencePool() {
+            return mReferencePool;
+        }
+
+        @Override
         public void addDestructionObserver(DestructionObserver destructionObserver) {}
 
         @Override
         public boolean isVisible() {
             return true;
         }
 
         @Override
         public SuggestionsEventReporter getEventReporter() {
             return mSuggestionsEventReporter;
         }
 
         @Override
         public SuggestionsNavigationDelegate getNavigationDelegate() {
             return null;
         }
     }
 
 }