Reland "Download home v2: Increase thumbnail cache size."

This is a reland of b859fdbb

Reason for reland: Link to a wrong crbug.

Original change's description:
> Download home v2: Increase thumbnail cache size.
>
> On Android we use an in-memory thumbnail cache to improve view recycling
> performance and use a disk cache to avoid costly backend operations like
> decoding images, videos etc.
>
> For download home v2, the thumbnail size is much larger than the old
> download home, thus we need to tweak the size of cache. 90% percentile
> of users have around 15 media thumbnails. The size of bitmap varies from
> under 1MB to around 5MB. The disk cache uses PNG to compress, the
> compression rate is around 1/3.
>
> This CL does the following:
>
> 1. The size of the thumbnail for high dpi devices are scaled down to
> mdpi, which can save memory/disk.
>
> 2. For in-memory cache size, download home v2 uses 15MB for high end
> devices. In-memory cache size is now passed in from owner of
> ThumbnailProviderImpl.
>
> 3. Disk cache size is increased. This should be shared by multiple
> owners of ThumbnailProviderImpl, or the owner with smaller disk cache
> size may remove files unexpectedly used by other owners.
>
> Bug: 87292
> Change-Id: If7cb700a60a8d119bca136b1a7d1fe7feb787d8b
> Reviewed-on: https://chromium-review.googlesource.com/c/1296546
> Commit-Queue: Xing Liu <xingliu@chromium.org>
> Reviewed-by: David Trainor <dtrainor@chromium.org>
> Reviewed-by: Shakti Sahu <shaktisahu@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#602957}

TBR=dtrainor@chromium.org,qinmin@chromium.org

Bug: 872925
Change-Id: Ida007e9255b033a48e259a214bf89431b25daafd
Reviewed-on: https://chromium-review.googlesource.com/c/1300684
Commit-Queue: Xing Liu <xingliu@chromium.org>
Reviewed-by: Xing Liu <xingliu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#603140}

chrome/android/java/src/org/chromium/chrome/browser/download/home/DownloadManagerUiConfig.java

@@ -4,6 +4,8 @@
 
 package org.chromium.chrome.browser.download.home;
 
+import static org.chromium.chrome.browser.util.ConversionUtils.BYTES_PER_MEGABYTE;
+
 import org.chromium.base.ContextUtils;
 import org.chromium.base.SysUtils;
 import org.chromium.chrome.browser.ChromeFeatureList;
@@ -32,6 +34,17 @@ public class DownloadManagerUiConfig {
      */
     public final boolean useNewDownloadPathThumbnails;
 
+    /**
+     * The in-memory thumbnail size in bytes.
+     */
+    public final int inMemoryThumbnailCacheSizeBytes;
+
+    /**
+     * The maximum thumbnail scale factor, thumbnail on higher dpi devices will downscale the
+     * quality to this level.
+     */
+    public final float maxThumbnailScaleFactor;
+
     /**
      * The time interval during which a download update is considered recent enough to show
      * in Just Now section.
@@ -46,6 +59,8 @@ public class DownloadManagerUiConfig {
         supportFullWidthImages = builder.mSupportFullWidthImages;
         useNewDownloadPath = builder.mUseNewDownloadPath;
         useNewDownloadPathThumbnails = builder.mUseNewDownloadPathThumbnails;
+        inMemoryThumbnailCacheSizeBytes = builder.mInMemoryThumbnailCacheSizeBytes;
+        maxThumbnailScaleFactor = builder.mMaxThumbnailScaleFactor;
         justNowThresholdSeconds = builder.mJustNowThresholdSeconds;
     }
 
@@ -56,12 +71,16 @@ public class DownloadManagerUiConfig {
         /** Default value for threshold time interval to show up in Just Now section. */
         private static final int JUST_NOW_THRESHOLD_SECONDS_DEFAULT = 30 * 60;
 
+        private static final int IN_MEMORY_THUMBNAIL_CACHE_SIZE_BYTES = 15 * BYTES_PER_MEGABYTE;
+
         private boolean mIsOffTheRecord;
         private boolean mIsSeparateActivity;
         private boolean mUseGenericViewTypes;
         private boolean mSupportFullWidthImages;
         private boolean mUseNewDownloadPath;
         private boolean mUseNewDownloadPathThumbnails;
+        private int mInMemoryThumbnailCacheSizeBytes = IN_MEMORY_THUMBNAIL_CACHE_SIZE_BYTES;
+        private float mMaxThumbnailScaleFactor = 1.f; /* mdpi scale factor. */
         private long mJustNowThresholdSeconds;
 
         public Builder() {
@@ -101,6 +120,16 @@ public class DownloadManagerUiConfig {
             return this;
         }
 
+        public Builder setInMemoryThumbnailCacheSizeBytes(int inMemoryThumbnailCacheSizeBytes) {
+            mInMemoryThumbnailCacheSizeBytes = inMemoryThumbnailCacheSizeBytes;
+            return this;
+        }
+
+        public Builder setMaxThumbnailScaleFactor(float maxThumbnailScaleFactor) {
+            mMaxThumbnailScaleFactor = maxThumbnailScaleFactor;
+            return this;
+        }
+
         public DownloadManagerUiConfig build() {
             return new DownloadManagerUiConfig(this);
         }

chrome/android/java/src/org/chromium/chrome/browser/download/home/glue/ThumbnailRequestGlue.java

@@ -7,6 +7,7 @@ package org.chromium.chrome.browser.download.home.glue;
 import android.graphics.Bitmap;
 
 import org.chromium.base.Callback;
+import org.chromium.base.ContextUtils;
 import org.chromium.chrome.browser.widget.ThumbnailProvider;
 import org.chromium.chrome.browser.widget.ThumbnailProvider.ThumbnailRequest;
 import org.chromium.chrome.browser.widget.ThumbnailProviderImpl;
@@ -14,6 +15,7 @@ import org.chromium.components.offline_items_collection.OfflineContentProvider;
 import org.chromium.components.offline_items_collection.OfflineItem;
 import org.chromium.components.offline_items_collection.OfflineItemVisuals;
 import org.chromium.components.offline_items_collection.VisualsCallback;
+import org.chromium.ui.display.DisplayAndroid;
 
 /**
  * Glue class responsible for connecting the current downloads and {@link OfflineContentProvider}
@@ -28,11 +30,15 @@ public class ThumbnailRequestGlue implements ThumbnailRequest {
 
     /** Creates a {@link ThumbnailRequestGlue} instance. */
     public ThumbnailRequestGlue(OfflineContentProviderGlue provider, OfflineItem item,
-            int iconWidthPx, int iconHeightPx, VisualsCallback callback) {
+            int iconWidthPx, int iconHeightPx, float maxThumbnailScaleFactor,
+            VisualsCallback callback) {
         mProvider = provider;
         mItem = item;
-        mIconWidthPx = iconWidthPx;
-        mIconHeightPx = iconHeightPx;
+
+        // Scale the thumbnail quality to mdpi for high dpi devices.
+        mIconWidthPx = downscaleThumbnailSize(iconWidthPx, maxThumbnailScaleFactor);
+        mIconHeightPx = downscaleThumbnailSize(iconHeightPx, maxThumbnailScaleFactor);
+
         mCallback = callback;
     }
 
@@ -90,4 +96,18 @@ public class ThumbnailRequestGlue implements ThumbnailRequest {
             }
         });
     }
+
+    /**
+     * Returns size in pixel used by the thumbnail request, considering dip scale factor.
+     * @param currentSize The current size before considering the dip scale factor.
+     * @param maxScaleFactor The maximum scale factor we expected to show as the thumbnail. Device
+     *                       with higher scale factor will be downscaled to this level.
+     */
+    private int downscaleThumbnailSize(int currentSize, float maxScaleFactor) {
+        DisplayAndroid display =
+                DisplayAndroid.getNonMultiDisplay(ContextUtils.getApplicationContext());
+        float scale = display.getDipScale();
+        if (scale <= maxScaleFactor) return currentSize;
+        return (int) (maxScaleFactor * currentSize / scale);
+    }
 }

chrome/android/java/src/org/chromium/chrome/browser/download/home/list/DateOrderedListMediator.java

@@ -74,6 +74,7 @@ class DateOrderedListMediator {
     private final ThumbnailProvider mThumbnailProvider;
     private final MediatorSelectionObserver mSelectionObserver;
     private final SelectionDelegate<ListItem> mSelectionDelegate;
+    private final DownloadManagerUiConfig mUiConfig;
 
     private final OffTheRecordOfflineItemFilter mOffTheRecordFilter;
     private final InvalidStateOfflineItemFilter mInvalidStateFilter;
@@ -140,6 +141,7 @@ class DateOrderedListMediator {
         mModel = model;
         mDeleteController = deleteController;
         mSelectionDelegate = selectionDelegate;
+        mUiConfig = config;
 
         mSource = new OfflineItemSource(mProvider);
         mOffTheRecordFilter = new OffTheRecordOfflineItemFilter(config.isOffTheRecord, mSource);
@@ -154,7 +156,8 @@ class DateOrderedListMediator {
 
         mSearchFilter.addObserver(new EmptyStateObserver(mSearchFilter, dateOrderedListObserver));
         mThumbnailProvider = new ThumbnailProviderImpl(
-                ((ChromeApplication) ContextUtils.getApplicationContext()).getReferencePool());
+                ((ChromeApplication) ContextUtils.getApplicationContext()).getReferencePool(),
+                config.inMemoryThumbnailCacheSizeBytes);
         mSelectionObserver = new MediatorSelectionObserver(selectionDelegate);
 
         mModel.getProperties().set(ListProperties.ENABLE_ITEM_ANIMATIONS, true);
@@ -358,8 +361,8 @@ class DateOrderedListMediator {
             return () -> {};
         }
 
-        ThumbnailRequest request =
-                new ThumbnailRequestGlue(mProvider, item, iconWidthPx, iconHeightPx, callback);
+        ThumbnailRequest request = new ThumbnailRequestGlue(mProvider, item, iconWidthPx,
+                iconHeightPx, mUiConfig.maxThumbnailScaleFactor, callback);
         mThumbnailProvider.getThumbnail(request);
         return () -> mThumbnailProvider.cancelRetrieval(request);
     }

chrome/android/java/src/org/chromium/chrome/browser/widget/ThumbnailDiskStorage.java

@@ -51,7 +51,7 @@ import java.util.LinkedHashSet;
 public class ThumbnailDiskStorage implements ThumbnailGeneratorCallback {
     private static final String TAG = "ThumbnailStorage";
     private static final int MAX_CACHE_BYTES =
-            ConversionUtils.BYTES_PER_MEGABYTE; // Max disk cache size is 1MB.
+            5 * ConversionUtils.BYTES_PER_MEGABYTE; // Max disk cache size is 5MB.
 
     // LRU cache of a pair of thumbnail's contentID and size. The order is based on the sequence of
     // add and get with the most recent at the end. The order at initialization (i.e. browser
@@ -76,6 +76,9 @@ public class ThumbnailDiskStorage implements ThumbnailGeneratorCallback {
 
     private ThumbnailStorageDelegate mDelegate;
 
+    // Maximum size in bytes for the disk cache.
+    private final int mMaxCacheBytes;
+
     // Number of bytes used in disk for cache.
     @VisibleForTesting
     long mSizeBytes;
@@ -174,10 +177,12 @@ public class ThumbnailDiskStorage implements ThumbnailGeneratorCallback {
     }
 
     @VisibleForTesting
-    ThumbnailDiskStorage(ThumbnailStorageDelegate delegate, ThumbnailGenerator thumbnailGenerator) {
+    ThumbnailDiskStorage(ThumbnailStorageDelegate delegate, ThumbnailGenerator thumbnailGenerator,
+            int maxCacheSizeBytes) {
         ThreadUtils.assertOnUiThread();
         mDelegate = delegate;
         mThumbnailGenerator = thumbnailGenerator;
+        mMaxCacheBytes = maxCacheSizeBytes;
         new InitTask().executeOnExecutor(AsyncTask.SERIAL_EXECUTOR);
     }
 
@@ -188,7 +193,7 @@ public class ThumbnailDiskStorage implements ThumbnailGeneratorCallback {
      * @return An instance of {@link ThumbnailDiskStorage}.
      */
     public static ThumbnailDiskStorage create(ThumbnailStorageDelegate delegate) {
-        return new ThumbnailDiskStorage(delegate, new ThumbnailGenerator());
+        return new ThumbnailDiskStorage(delegate, new ThumbnailGenerator(), MAX_CACHE_BYTES);
     }
 
     /**
@@ -391,12 +396,12 @@ public class ThumbnailDiskStorage implements ThumbnailGeneratorCallback {
     }
 
     /**
-     * Trim the cache to stay under the MAX_CACHE_BYTES limit by removing the oldest entries.
+     * Trim the cache to stay under the max cache size by removing the oldest entries.
      */
     @VisibleForTesting
     void trim() {
         ThreadUtils.assertOnBackgroundThread();
-        while (mSizeBytes > MAX_CACHE_BYTES) {
+        while (mSizeBytes > mMaxCacheBytes) {
             removeFromDiskHelper(sDiskLruCache.iterator().next());
         }
     }
@@ -476,10 +481,9 @@ public class ThumbnailDiskStorage implements ThumbnailGeneratorCallback {
      * Get directory for thumbnail entries in the designated app (internal) cache directory.
      * The directory's name must be unique.
      * @param context The application's context.
-     * @param uniqueName The name of the thumbnail directory. Must be unique.
      * @return The path to the thumbnail cache directory.
      */
     private static File getDiskCacheDir(Context context, String thumbnailDirName) {
         return new File(context.getCacheDir().getPath() + File.separator + thumbnailDirName);
     }
-}
\ No newline at end of file
+}

chrome/android/java/src/org/chromium/chrome/browser/widget/ThumbnailProviderImpl.java

@@ -31,14 +31,18 @@ import java.util.Locale;
  *                    duplicating work to decode the same image for two different requests.
  */
 public class ThumbnailProviderImpl implements ThumbnailProvider, ThumbnailStorageDelegate {
-    /** 5 MB of thumbnails should be enough for everyone. */
-    private static final int MAX_CACHE_BYTES = 5 * ConversionUtils.BYTES_PER_MEGABYTE;
+    /** Default in-memory thumbnail cache size. */
+    private static final int DEFAULT_MAX_CACHE_BYTES = 5 * ConversionUtils.BYTES_PER_MEGABYTE;
 
     /**
      * Helper object to store in the LruCache when we don't really need a value but can't use null.
      */
     private static final Object NO_BITMAP_PLACEHOLDER = new Object();
 
+    /**
+     * An in-memory LRU cache used to cache bitmaps, mostly improve performance for scrolling, when
+     * the view is recycled and needs a new thumbnail.
+     */
     private BitmapCache mBitmapCache;
 
     /**
@@ -57,9 +61,22 @@ public class ThumbnailProviderImpl implements ThumbnailProvider, ThumbnailStorag
 
     private ThumbnailDiskStorage mStorage;
 
+    /**
+     * Constructor to build the thumbnail provider with default thumbnail cache size.
+     * @param referencePool The application's reference pool.
+     */
     public ThumbnailProviderImpl(DiscardableReferencePool referencePool) {
+        this(referencePool, DEFAULT_MAX_CACHE_BYTES);
+    }
+
+    /**
+     * Constructor to build the thumbnail provider.
+     * @param referencePool The application's reference pool.
+     * @param bitmapCacheSizeByte The size in bytes of the in-memory LRU bitmap cache.
+     */
+    public ThumbnailProviderImpl(DiscardableReferencePool referencePool, int bitmapCacheSizeByte) {
         ThreadUtils.assertOnUiThread();
-        mBitmapCache = new BitmapCache(referencePool, MAX_CACHE_BYTES);
+        mBitmapCache = new BitmapCache(referencePool, bitmapCacheSizeByte);
         mStorage = ThumbnailDiskStorage.create(this);
     }
 

chrome/android/javatests/src/org/chromium/chrome/browser/widget/ThumbnailDiskStorageTest.java

@@ -18,6 +18,7 @@ import org.junit.runner.RunWith;
 
 import org.chromium.base.ThreadUtils;
 import org.chromium.base.test.util.UrlUtils;
+import org.chromium.chrome.browser.util.ConversionUtils;
 import org.chromium.chrome.test.ChromeJUnit4ClassRunner;
 import org.chromium.content_public.browser.test.util.Criteria;
 import org.chromium.content_public.browser.test.util.CriteriaHelper;
@@ -42,6 +43,7 @@ public class ThumbnailDiskStorageTest {
     private static final Bitmap BITMAP2 = BitmapFactory.decodeFile(FILE_PATH2);
     private static final int ICON_WIDTH1 = 50;
     private static final int ICON_WIDTH2 = 70;
+    private static final int TEST_MAX_CACHE_BYTES = 1 * ConversionUtils.BYTES_PER_MEGABYTE;
 
     private static final long TIMEOUT_MS = 10000;
     private static final long INTERVAL_MS = 500;
@@ -98,9 +100,9 @@ public class ThumbnailDiskStorageTest {
         // Accessed by test and UI threads.
         public final AtomicBoolean initialized = new AtomicBoolean();
 
-        public TestThumbnailDiskStorage(
-                TestThumbnailStorageDelegate delegate, TestThumbnailGenerator thumbnailGenerator) {
-            super(delegate, thumbnailGenerator);
+        public TestThumbnailDiskStorage(TestThumbnailStorageDelegate delegate,
+                TestThumbnailGenerator thumbnailGenerator, int maxCacheSizeBytes) {
+            super(delegate, thumbnailGenerator, maxCacheSizeBytes);
         }
 
         @Override
@@ -159,8 +161,9 @@ public class ThumbnailDiskStorageTest {
         ThreadUtils.runOnUiThreadBlocking(new Runnable() {
             @Override
             public void run() {
-                mTestThumbnailDiskStorage = new TestThumbnailDiskStorage(
-                        mTestThumbnailStorageDelegate, mTestThumbnailGenerator);
+                mTestThumbnailDiskStorage =
+                        new TestThumbnailDiskStorage(mTestThumbnailStorageDelegate,
+                                mTestThumbnailGenerator, TEST_MAX_CACHE_BYTES);
                 // Clear the disk cache so that cached entries from previous runs won't show up.
                 mTestThumbnailDiskStorage.clear();
             }