[Impeller] Release a texture during Playground teardown (#45832)

Closes flutter/flutter#134678.

Partial work towards flutter/flutter#133708, flutter/flutter#133506.

This gets us closer to being able to run `aiks_unittests` with validations enabled, removing a VMA allocation error:

## Before

```txt
Note: Google Test filter = Play/AiksTest.ReleasesTextureOnTeardown/Vulkan
[==========] Running 1 test from 1 test suite.
[----------] Global test environment set-up.
[----------] 1 test from Play/AiksTest
[ RUN      ] Play/AiksTest.ReleasesTextureOnTeardown/Vulkan
[INFO:capabilities_vk.cc(50)] Vulkan validations are enabled.
[FATAL:third_party/vulkan_memory_allocator/include/vk_mem_alloc.h(6179)] Check failed: (false && "Unfreed dedicated allocations found!"). Vulkan Memory Allocator Failure!
```

## After

```txt
Note: Google Test filter = Play/AiksTest.ReleasesTextureOnTeardown/Vulkan
[==========] Running 1 test from 1 test suite.
[----------] Global test environment set-up.
[----------] 1 test from Play/AiksTest
[ RUN      ] Play/AiksTest.ReleasesTextureOnTeardown/Vulkan
[INFO:capabilities_vk.cc(50)] Vulkan validations are enabled.
[       OK ] Play/AiksTest.ReleasesTextureOnTeardown/Vulkan (1192 ms)
[----------] 1 test from Play/AiksTest (1192 ms total)

[----------] Global test environment tear-down
[==========] 1 test from 1 test suite ran. (1192 ms total)
[  PASSED  ] 1 test.
```

---

Added a test that will catch regressions.

Author: matanlurey

impeller/aiks/aiks_playground.cc

@@ -23,6 +23,11 @@ void AiksPlayground::SetTypographerContext(
   typographer_context_ = std::move(typographer_context);
 }
 
+void AiksPlayground::TearDown() {
+  inspector_.HackResetDueToTextureLeaks();
+  PlaygroundTest::TearDown();
+}
+
 bool AiksPlayground::OpenPlaygroundHere(Picture picture) {
   return OpenPlaygroundHere([&picture](AiksContext& renderer) -> Picture {
     return std::move(picture);

impeller/aiks/aiks_playground.h

@@ -22,6 +22,8 @@ class AiksPlayground : public PlaygroundTest {
 
   ~AiksPlayground();
 
+  void TearDown() override;
+
   void SetTypographerContext(
       std::shared_ptr<TypographerContext> typographer_context);
 

impeller/aiks/aiks_playground_inspector.cc

@@ -63,6 +63,10 @@ const std::optional<Picture>& AiksInspector::RenderInspector(
   return last_picture_;
 }
 
+void AiksInspector::HackResetDueToTextureLeaks() {
+  last_picture_.reset();
+}
+
 static const auto kPropertiesProcTable = CaptureProcTable{
     .boolean =
         [](CaptureBooleanProperty& p) {

impeller/aiks/aiks_playground_inspector.h

@@ -21,6 +21,17 @@ class AiksInspector {
       AiksContext& aiks_context,
       const std::function<std::optional<Picture>()>& picture_callback);
 
+  // Resets (releases) the underlying |Picture| object.
+  //
+  // Underlying issue: <https://github.com/flutter/flutter/issues/134678>.
+  //
+  // The tear-down code is not running in the right order; we still have a
+  // reference to the |Picture| object when the |Context| is being destroyed,
+  // which causes the |Texture| objects to leak.
+  //
+  // TODO(matanlurey): https://github.com/flutter/flutter/issues/134748.
+  void HackResetDueToTextureLeaks();
+
  private:
   void RenderCapture(CaptureContext& capture_context);
   void RenderCaptureElement(CaptureElement& element);

impeller/aiks/aiks_unittests.cc

@@ -3409,5 +3409,38 @@ TEST_P(AiksTest, CaptureInactivatedByDefault) {
   ASSERT_FALSE(GetContext()->capture.IsActive());
 }
 
+// Regression test for https://github.com/flutter/flutter/issues/134678.
+TEST_P(AiksTest, ReleasesTextureOnTeardown) {
+  auto context = GetContext();
+  std::weak_ptr<Texture> weak_texture;
+
+  {
+    auto texture = CreateTextureForFixture("table_mountain_nx.png");
+
+    Canvas canvas;
+    canvas.Scale(GetContentScale());
+    canvas.Translate({100.0f, 100.0f, 0});
+
+    Paint paint;
+    paint.color_source = ColorSource::MakeImage(
+        texture, Entity::TileMode::kClamp, Entity::TileMode::kClamp, {}, {});
+    canvas.DrawRect({0, 0, 600, 600}, paint);
+
+    ASSERT_TRUE(OpenPlaygroundHere(canvas.EndRecordingAsPicture()));
+  }
+
+  // See https://github.com/flutter/flutter/issues/134751.
+  //
+  // If the fence waiter was working this may not be released by the end of the
+  // scope above. Adding a manual shutdown so that future changes to the fence
+  // waiter will not flake this test.
+  context->Shutdown();
+
+  // The texture should be released by now.
+  ASSERT_TRUE(weak_texture.expired()) << "When the texture is no longer in use "
+                                         "by the backend, it should be "
+                                         "released.";
+}
+
 }  // namespace testing
 }  // namespace impeller