Avoid using ConvertToBaseOnceCallback needlessly

... in AnimationWorkletMutatorDispatcher code.

Since the code in case is within Blink, there is no
need to convert the WTF::CrossThreadOnceFunction to
base::OnceCallback (with ConvertToBaseOnceCallback).

CL adopts the use of WTF::CrossThreadOnceFunction to
simplify the code.

BUG=963574
R=haraken@chromium.org, hiroshige@chromium.org

Change-Id: I8586dc1397f0861bb42c59dd88bfb7defc534b66
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1625969
Auto-Submit: Antonio Gomes <tonikitoo@igalia.com>
Commit-Queue: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#662529}

third_party/blink/renderer/platform/graphics/animation_worklet_mutator_dispatcher.h

@@ -8,6 +8,7 @@
 #include "base/bind.h"
 #include "third_party/blink/renderer/platform/graphics/animation_worklet_mutators_state.h"
 #include "third_party/blink/renderer/platform/platform_export.h"
+#include "third_party/blink/renderer/platform/wtf/functional.h"
 
 namespace blink {
 
@@ -15,7 +16,8 @@ class PLATFORM_EXPORT AnimationWorkletMutatorDispatcher {
  public:
   virtual ~AnimationWorkletMutatorDispatcher() = default;
 
-  using AsyncMutationCompleteCallback = base::OnceCallback<void(MutateStatus)>;
+  using AsyncMutationCompleteCallback =
+      WTF::CrossThreadOnceFunction<void(MutateStatus)>;
 
   // Run the animation frame callbacks from all connected AnimationWorklets.
   virtual void MutateSynchronously(

third_party/blink/renderer/platform/graphics/animation_worklet_mutator_dispatcher_impl_test.cc

@@ -360,28 +360,26 @@ class AnimationWorkletMutatorDispatcherImplAsyncTest
  public:
   AnimationWorkletMutatorDispatcher::AsyncMutationCompleteCallback
   CreateIntermediateResultCallback(MutateStatus expected_result) {
-    return ConvertToBaseOnceCallback(
-        CrossThreadBindOnce(&AnimationWorkletMutatorDispatcherImplAsyncTest ::
-                                VerifyExpectedMutationResult,
-                            CrossThreadUnretained(this), expected_result));
+    return CrossThreadBindOnce(
+        &AnimationWorkletMutatorDispatcherImplAsyncTest ::
+            VerifyExpectedMutationResult,
+        CrossThreadUnretained(this), expected_result);
   }
 
   AnimationWorkletMutatorDispatcher::AsyncMutationCompleteCallback
   CreateNotReachedCallback() {
-    return ConvertToBaseOnceCallback(
-        CrossThreadBindOnce([](MutateStatus unused) {
-          NOTREACHED()
-              << "Mutate complete callback should not have been triggered";
-        }));
+    return CrossThreadBindOnce([](MutateStatus unused) {
+      NOTREACHED() << "Mutate complete callback should not have been triggered";
+    });
   }
 
   AnimationWorkletMutatorDispatcher::AsyncMutationCompleteCallback
   CreateTestCompleteCallback(
       MutateStatus expected_result = MutateStatus::kCompletedWithUpdate) {
-    return ConvertToBaseOnceCallback(
-        CrossThreadBindOnce(&AnimationWorkletMutatorDispatcherImplAsyncTest ::
-                                VerifyCompletedMutationResultAndFinish,
-                            CrossThreadUnretained(this), expected_result));
+    return CrossThreadBindOnce(
+        &AnimationWorkletMutatorDispatcherImplAsyncTest ::
+            VerifyCompletedMutationResultAndFinish,
+        CrossThreadUnretained(this), expected_result);
   }
 
   // Executes run loop until quit closure is called.

third_party/blink/renderer/platform/graphics/compositor_mutator_client.cc

@@ -6,6 +6,7 @@
 
 #include <memory>
 #include "base/trace_event/trace_event.h"
+#include "third_party/blink/renderer/platform/cross_thread_functional.h"
 #include "third_party/blink/renderer/platform/graphics/animation_worklet_mutator_dispatcher_impl.h"
 
 namespace blink {
@@ -28,8 +29,9 @@ bool CompositorMutatorClient::Mutate(
     MutateQueuingStrategy queueing_strategy,
     DoneCallback on_done) {
   TRACE_EVENT0("cc", "CompositorMutatorClient::Mutate");
-  return mutator_->MutateAsynchronously(std::move(input_state),
-                                        queueing_strategy, std::move(on_done));
+  return mutator_->MutateAsynchronously(
+      std::move(input_state), queueing_strategy,
+      CrossThreadBindOnce(std::move(on_done)));
 }
 
 void CompositorMutatorClient::SetMutationUpdate(