[IC] Add unit test for null callback behavior that was previously fixed

The bug was fixed, but I didn't add a unittest. This unittest will
cover the case fixed in 1351534.

Bug: 909735
Change-Id: Ie9337b301abcd7717c0719741d9e8d58adafade0
Reviewed-on: https://chromium-review.googlesource.com/c/1358922Reviewed-by: Sky Malice <skym@chromium.org>
Reviewed-by: Filip Gorski <fgorski@chromium.org>
Commit-Queue: Brandon Wylie <wylieb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#613380}

components/image_fetcher/core/cache/image_cache_unittest.cc

@@ -36,6 +36,7 @@ constexpr char kCachedImageFetcherEventHistogramName[] =
 constexpr char kImageUrl[] = "http://gstatic.img.com/foo.jpg";
 constexpr char kImageUrlHashed[] = "3H7UODDH3WKDWK6FQ3IZT3LQMVBPYJ4M";
 constexpr char kImageData[] = "data";
+const int kOverMaxCacheSize = 65 * 1024 * 1024;
 
 }  // namespace
 
@@ -97,6 +98,17 @@ class ImageCacheTest : public testing::Test {
     RunUntilIdle();
   }
 
+  void RunEvictionWhenFull(bool success) {
+    image_cache()->RunEvictionWhenFull();
+
+    if (success) {
+      db()->LoadCallback(true);
+      db()->UpdateCallback(true);
+    }
+
+    RunUntilIdle();
+  }
+
   bool IsMetadataPresent(const std::string& key) {
     return db_store_.find(key) != db_store_.end();
   }
@@ -291,6 +303,20 @@ TEST_F(ImageCacheTest, Eviction) {
       CachedImageFetcherEvent::kCacheStartupEvictionFinished, 1);
 }
 
+TEST_F(ImageCacheTest, EvictionWhenFull) {
+  PrepareImageCache();
+  InjectMetadata(kImageUrl, kOverMaxCacheSize);
+  clock()->SetNow(clock()->Now() + base::TimeDelta::FromDays(6));
+  RunEvictionWhenFull(/* success */ true);
+
+  // The data should be removed because it's over the allowed limit.
+  EXPECT_CALL(*this, DataCallback(""));
+  image_cache()->LoadImage(
+      false, kImageUrl,
+      base::BindOnce(&ImageCacheTest::DataCallback, base::Unretained(this)));
+  RunUntilIdle();
+}
+
 TEST_F(ImageCacheTest, EvictionTooSoon) {
   PrepareImageCache();