Remove release fence flags

ce_fence_promise and screenshot_fence_preservation flags
have been out for several releases. They can be deleted,
along with any obsolete code related to the flag removal.

Bug: 351894825
Test: atest SurfaceFlinger_test
Flag: EXEMPT flag removal
Change-Id: Iba6166358c96ff6cfe5c64b68640fcd992c4089f
diff --git a/services/surfaceflinger/Layer.cpp b/services/surfaceflinger/Layer.cpp
index c14769e..e5dc2ee 100644
--- a/services/surfaceflinger/Layer.cpp
+++ b/services/surfaceflinger/Layer.cpp
@@ -751,54 +751,6 @@
     }
 }
 
-void Layer::onLayerDisplayed(ftl::SharedFuture<FenceResult> futureFenceResult,
-                             ui::LayerStack layerStack,
-                             std::function<FenceResult(FenceResult)>&& continuation) {
-    sp<CallbackHandle> ch = findCallbackHandle();
-
-    if (!FlagManager::getInstance().screenshot_fence_preservation() && continuation) {
-        futureFenceResult = ftl::Future(futureFenceResult).then(std::move(continuation)).share();
-    }
-
-    if (ch != nullptr) {
-        ch->previousReleaseCallbackId = mPreviousReleaseCallbackId;
-        ch->previousSharedReleaseFences.emplace_back(std::move(futureFenceResult));
-        ch->name = mName;
-    } else if (FlagManager::getInstance().screenshot_fence_preservation()) {
-        // If we didn't get a release callback yet, e.g. some scenarios when capturing screenshots
-        // asynchronously, then make sure we don't drop the fence.
-        mPreviousReleaseFenceAndContinuations.emplace_back(std::move(futureFenceResult),
-                                                           std::move(continuation));
-        std::vector<FenceAndContinuation> mergedFences;
-        sp<Fence> prevFence = nullptr;
-        // For a layer that's frequently screenshotted, try to merge fences to make sure we don't
-        // grow unbounded.
-        for (const auto& futureAndContinuation : mPreviousReleaseFenceAndContinuations) {
-            auto result = futureAndContinuation.future.wait_for(0s);
-            if (result != std::future_status::ready) {
-                mergedFences.emplace_back(futureAndContinuation);
-                continue;
-            }
-
-            mergeFence(getDebugName(),
-                       futureAndContinuation.chain().get().value_or(Fence::NO_FENCE), prevFence);
-        }
-        if (prevFence != nullptr) {
-            mergedFences.emplace_back(ftl::yield(FenceResult(std::move(prevFence))).share());
-        }
-
-        mPreviousReleaseFenceAndContinuations.swap(mergedFences);
-    }
-
-    if (mBufferInfo.mBuffer) {
-        mPreviouslyPresentedLayerStacks.push_back(layerStack);
-    }
-
-    if (mDrawingState.frameNumber > 0) {
-        mDrawingState.previousFrameNumber = mDrawingState.frameNumber;
-    }
-}
-
 void Layer::releasePendingBuffer(nsecs_t dequeueReadyTime) {
     for (const auto& handle : mDrawingState.callbackHandles) {
         handle->bufferReleaseChannel = mBufferReleaseChannel;
@@ -1111,22 +1063,13 @@
             handle->acquireTimeOrFence = mCallbackHandleAcquireTimeOrFence;
             handle->frameNumber = mDrawingState.frameNumber;
             handle->previousFrameNumber = mDrawingState.previousFrameNumber;
-            if (FlagManager::getInstance().ce_fence_promise() &&
-                mPreviousReleaseBufferEndpoint == handle->listener) {
+            if (mPreviousReleaseBufferEndpoint == handle->listener) {
                 // Add fence from previous screenshot now so that it can be dispatched to the
                 // client.
                 for (auto& [_, future] : mAdditionalPreviousReleaseFences) {
                     handle->previousReleaseFences.emplace_back(std::move(future));
                 }
                 mAdditionalPreviousReleaseFences.clear();
-            } else if (FlagManager::getInstance().screenshot_fence_preservation() &&
-                       mPreviousReleaseBufferEndpoint == handle->listener) {
-                // Add fences from previous screenshots now so that they can be dispatched to the
-                // client.
-                for (const auto& futureAndContinution : mPreviousReleaseFenceAndContinuations) {
-                    handle->previousSharedReleaseFences.emplace_back(futureAndContinution.chain());
-                }
-                mPreviousReleaseFenceAndContinuations.clear();
             }
             // Store so latched time and release fence can be set
             mDrawingState.callbackHandles.push_back(handle);