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

chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetArticleViewHolder.java

Index: chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetArticleViewHolder.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetArticleViewHolder.java b/chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetArticleViewHolder.java
index 01810870423cb8abcecb5aba852aa8e27b431683..fd6dbdd83d93c9859603998d2f8f767ea050c40d 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetArticleViewHolder.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetArticleViewHolder.java
@@ -354,7 +354,7 @@ public class SnippetArticleViewHolder extends CardViewHolder implements Impressi
             mArticle.setThumbnailBitmap(null);
             Bitmap thumbnail = mThumbnailProvider.getThumbnail(mImageCallback);
             if (thumbnail == null || thumbnail.isRecycled()) return;
-            mArticle.setThumbnailBitmap(thumbnail);
+            mArticle.setThumbnailBitmap(mUiDelegate.getReferencePool().put(thumbnail));
             setThumbnailFromBitmap(thumbnail);
 
             return;
@@ -369,8 +369,9 @@ public class SnippetArticleViewHolder extends CardViewHolder implements Impressi
 
         // mThumbnailView's visibility is modified in updateLayout().
         if (mThumbnailView.getVisibility() != View.VISIBLE) return;
-        if (mArticle.getThumbnailBitmap() != null && !mArticle.getThumbnailBitmap().isRecycled()) {
-            setThumbnailFromBitmap(mArticle.getThumbnailBitmap());
+        Bitmap thumbnail = mArticle.getThumbnailBitmap();
+        if (thumbnail != null && !thumbnail.isRecycled()) {
+            setThumbnailFromBitmap(thumbnail);
             return;
         }
 
@@ -416,7 +417,7 @@ public class SnippetArticleViewHolder extends CardViewHolder implements Impressi
                 thumbnail, targetSize, targetSize, ThumbnailUtils.OPTIONS_RECYCLE_INPUT);
 
         // Store the bitmap to skip the download task next time we display this snippet.
-        snippet.setThumbnailBitmap(scaledThumbnail);
+        snippet.setThumbnailBitmap(mUiDelegate.getReferencePool().put(scaledThumbnail));
 
         // Cross-fade between the placeholder and the thumbnail. We cross-fade because the incoming
         // image may have transparency and we don't want the previous image showing up behind.