cc: Interface to evict images from cc image decode cache.

cc/tiles/gpu_image_decode_cache_unittest.cc

Index: cc/tiles/gpu_image_decode_cache_unittest.cc
diff --git a/cc/tiles/gpu_image_decode_cache_unittest.cc b/cc/tiles/gpu_image_decode_cache_unittest.cc
index d46fa18a461bf426c8d5d5195800bbe5ca2c6a23..1bedc63ad86fc0dac2c26048f0c0f35274b6f4a5 100644
--- a/cc/tiles/gpu_image_decode_cache_unittest.cc
+++ b/cc/tiles/gpu_image_decode_cache_unittest.cc
@@ -1714,5 +1714,42 @@ TEST(GpuImageDecodeCacheTest, GetTaskForImageDifferentColorSpace) {
   cache.UnrefImage(third_draw_image);
 }
 
+TEST(GpuImageDecodeCacheTest, RemoveUnusedImage) {

[ericrk, 2017/06/19 17:09:30]

Not needed right now, but I wonder if we should move some number of tests to a
"Common Image Decode Cache Test" file, where we can just parameterize the test
by GPU/SW. Certainly for some tests we want to test per-cache behavior, but for
many (this one), it would be nice to keep the test uniform.

[sohan, 2017/06/20 13:31:39]

If we remove this test for future, we are essentially pushing in an un-tested
code, will it be a good practice ?

Maybe once we implement the evict logic in both the caches, we can start moving
the common tests as you pointed. wdyt ?

[ericrk, 2017/06/20 16:06:05]

SGTM, thanks

+  auto context_provider = TestContextProvider::Create();
+  context_provider->BindToCurrentThread();
+  TestGpuImageDecodeCache cache(context_provider.get());
+  bool is_decomposable = true;
+  SkFilterQuality quality = kHigh_SkFilterQuality;
+  std::vector<uint32_t> unique_ids(10);
+
+  for (int i = 0; i < 10; ++i) {
+    sk_sp<SkImage> image = CreateImage(100, 100);
+    unique_ids[i] = image->uniqueID();
+    DrawImage draw_image(
+        CreatePaintImage(image),
+        SkIRect::MakeWH(image->width(), image->height()), quality,
+        CreateMatrix(SkSize::Make(1.0f, 1.0f), is_decomposable),
+        DefaultColorSpace());
+    scoped_refptr<TileTask> task;
+    bool need_unref = cache.GetTaskForImageAndRef(
+        draw_image, ImageDecodeCache::TracingInfo(), &task);
+    EXPECT_TRUE(need_unref);
+    EXPECT_TRUE(task);
+    TestTileTaskRunner::ProcessTask(task->dependencies()[0].get());
+    TestTileTaskRunner::ProcessTask(task.get());
+    cache.UnrefImage(draw_image);
+  }
+
+  // We should now have data image in our cache.
+  EXPECT_GT(cache.GetBytesUsedForTesting(), 0u);
+  EXPECT_EQ(cache.GetNumCacheEntriesForTesting(), 10u);
+
+  // Remove unused ids.
+  for (uint32_t i = 0; i < 10; ++i) {
+    cache.NotifyImageUnused(unique_ids[i]);
+    EXPECT_EQ(cache.GetNumCacheEntriesForTesting(), (10 - i - 1));
+  }
+}
+
 }  // namespace
 }  // namespace cc