[IC] Scale images before storing them in memory and returning

Scaling/cropping images we get for Feed, yields a roughly 5x
decrease in memory usage.

Image size before: 1064160 bytes
Image size after:  188356  bytes

Bug: 910192
Change-Id: I7b4347c9e34f6f8680886bb2c0dd14f5b4346ebe
Reviewed-on: https://chromium-review.googlesource.com/c/1357608
Commit-Queue: Brandon Wylie <wylieb@chromium.org>
Reviewed-by: Theresa <twellington@chromium.org>
Reviewed-by: Sky Malice <skym@chromium.org>
Cr-Commit-Position: refs/heads/master@{#613372}

chrome/android/java/src/org/chromium/chrome/browser/cached_image_fetcher/InMemoryCachedImageFetcher.java

@@ -5,6 +5,7 @@
 package org.chromium.chrome.browser.cached_image_fetcher;
 
 import android.graphics.Bitmap;
+import android.media.ThumbnailUtils;
 
 import org.chromium.base.Callback;
 import org.chromium.base.DiscardableReferencePool;
@@ -63,6 +64,7 @@ public class InMemoryCachedImageFetcher implements CachedImageFetcher {
             }
 
             mCachedImageFetcher.fetchImage(url, width, height, (Bitmap bitmap) -> {
+                bitmap = tryToResizeImage(bitmap, width, height);
                 storeBitmap(bitmap, url, width, height);
                 callback.onResult(bitmap);
             });
@@ -140,6 +142,32 @@ public class InMemoryCachedImageFetcher implements CachedImageFetcher {
         return Math.min(maxCacheUsage, preferredCacheSize);
     }
 
+    /**
+     * Try to resize the given image if the conditions are met.
+     *
+     * @param bitmap The input bitmap, will be recycled if scaled.
+     * @param width The desired width of the output.
+     * @param height The desired height of the output.
+     *
+     * @return The resized image, or the original image if the  conditions aren't met.
+     */
+    @VisibleForTesting
+    Bitmap tryToResizeImage(Bitmap bitmap, int width, int height) {
+        if (width != 0 && height != 0 && bitmap.getWidth() != width
+                && bitmap.getHeight() != height) {
+            /* The resizing rules are the as follows:
+               (1) The image will be scaled up (if smaller) in a way that maximizes the area of the
+               source bitmap that's in the destination bitmap.
+               (2) A crop is made in the middle of the bitmap for the given size (width, height).
+               The x/y are placed appropriately (conceptually just think of it as a properly sized
+               chunk taken from the middle). */
+            return ThumbnailUtils.extractThumbnail(
+                    bitmap, width, height, ThumbnailUtils.OPTIONS_RECYCLE_INPUT);
+        } else {
+            return bitmap;
+        }
+    }
+
     /** Test constructor. */
     @VisibleForTesting
     InMemoryCachedImageFetcher(BitmapCache bitmapCache, CachedImageFetcher cachedImageFetcher) {

chrome/android/junit/src/org/chromium/chrome/browser/cached_image_fetcher/InMemoryCachedImageFetcherTest.java

@@ -4,6 +4,8 @@
 
 package org.chromium.chrome.browser.cached_image_fetcher;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotEquals;
 import static org.junit.Assert.fail;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.eq;
@@ -36,6 +38,7 @@ import org.chromium.chrome.browser.BitmapCache;
 /**
  * Unit tests for InMemoryCachedImageFetcher.
  */
+@SuppressWarnings("unchecked")
 @RunWith(BaseRobolectricTestRunner.class)
 @Config(manifest = Config.NONE)
 public class InMemoryCachedImageFetcherTest {
@@ -68,6 +71,8 @@ public class InMemoryCachedImageFetcherTest {
         MockitoAnnotations.initMocks(this);
         mReferencePool = new DiscardableReferencePool();
         mBitmapCache = new BitmapCache(mReferencePool, DEFAULT_CACHE_SIZE);
+        mInMemoryCachedImageFetcher =
+                spy(new InMemoryCachedImageFetcher(mBitmapCache, mCachedImageFetcherImpl));
     }
 
     @After
@@ -93,9 +98,12 @@ public class InMemoryCachedImageFetcherTest {
                 .fetchImage(eq(URL), mWidthCaptor.capture(), mHeightCaptor.capture(),
                         mCallbackCaptor.capture());
         // clang-format on
+
+        doReturn(bitmap)
+                .when(mInMemoryCachedImageFetcher)
+                .tryToResizeImage(eq(bitmap), eq(WIDTH_PX), eq(HEIGHT_PX));
     }
 
-    @SuppressWarnings("unchecked")
     @Test
     @SmallTest
     public void testFetchImageCachesFirstCall() throws Exception {
@@ -126,6 +134,27 @@ public class InMemoryCachedImageFetcherTest {
                 .fetchImage(eq(URL), eq(WIDTH_PX), eq(HEIGHT_PX), any());
     }
 
+    @Test
+    @SmallTest
+    public void testResize() throws Exception {
+        Bitmap result =
+                mInMemoryCachedImageFetcher.tryToResizeImage(mBitmap, WIDTH_PX / 2, HEIGHT_PX / 2);
+        assertNotEquals(result, mBitmap);
+    }
+
+    @Test
+    @SmallTest
+    public void testResizeBailsOutIfSizeIsZero() throws Exception {
+        Bitmap result = mInMemoryCachedImageFetcher.tryToResizeImage(mBitmap, 0, HEIGHT_PX);
+        assertEquals(result, mBitmap);
+
+        result = mInMemoryCachedImageFetcher.tryToResizeImage(mBitmap, WIDTH_PX, 0);
+        assertEquals(result, mBitmap);
+
+        result = mInMemoryCachedImageFetcher.tryToResizeImage(mBitmap, 0, 0);
+        assertEquals(result, mBitmap);
+    }
+
     @Test
     @SmallTest
     public void testFetchImageDoesNotCacheAfterDestroy() {