Enable single hop screenshots for only threaded re

Fixes a deadlock where screenshot requests are blocked
on the main thread which inturn is blocked by the
screenshot request finishing.

Flag: EXEMPT bug fix
Bug: 349776684
Bug: 349741485
Bug: 352267188
Test: presubmit
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:5aadd249f326b21e5ef6cadfebc15b6a0a016816)
Merged-In: Ibf038ad6db3e87c84508d3e101ca1eb144836d7c
Change-Id: Ibf038ad6db3e87c84508d3e101ca1eb144836d7c

Author: nairvis-beep

services/surfaceflinger/RegionSamplingThread.cpp

@@ -356,7 +356,7 @@ void RegionSamplingThread::captureSample() {
 
     FenceResult fenceResult;
     if (FlagManager::getInstance().single_hop_screenshot() &&
-        FlagManager::getInstance().ce_fence_promise()) {
+        FlagManager::getInstance().ce_fence_promise() && mFlinger.mRenderEngine->isThreaded()) {
         std::vector<sp<LayerFE>> layerFEs;
         auto displayState =
                 mFlinger.getDisplayAndLayerSnapshotsFromMainThread(renderAreaBuilder,

services/surfaceflinger/SurfaceFlinger.cpp

@@ -8184,7 +8184,7 @@ void SurfaceFlinger::captureScreenCommon(RenderAreaBuilderVariant renderAreaBuil
     }
 
     if (FlagManager::getInstance().single_hop_screenshot() &&
-        FlagManager::getInstance().ce_fence_promise()) {
+        FlagManager::getInstance().ce_fence_promise() && mRenderEngine->isThreaded()) {
         std::vector<sp<LayerFE>> layerFEs;
         auto displayState =
                 getDisplayAndLayerSnapshotsFromMainThread(renderAreaBuilder, getLayerSnapshotsFn,
@@ -8558,10 +8558,8 @@ ftl::SharedFuture<FenceResult> SurfaceFlinger::renderScreenImpl(
     // to CompositionEngine::present.
     ftl::SharedFuture<FenceResult> presentFuture;
     if (FlagManager::getInstance().single_hop_screenshot() &&
-        FlagManager::getInstance().ce_fence_promise()) {
-        presentFuture = mRenderEngine->isThreaded()
-                ? ftl::yield(present()).share()
-                : mScheduler->schedule(std::move(present)).share();
+        FlagManager::getInstance().ce_fence_promise() && mRenderEngine->isThreaded()) {
+        presentFuture = ftl::yield(present()).share();
     } else {
         presentFuture = mRenderEngine->isThreaded() ? ftl::defer(std::move(present)).share()
                                                     : ftl::yield(present()).share();