Fix FenceTracker releaseFence

This patch:
* Fixes the release fence when GPU compositing.
* Stores the final release fence in ConsumerBase just
    before releasing the Buffer, which helps ensure
    sync points aren't added unknowningly.
* Makes HWC2 release pending buffers as the first step
    of postCompostion, rather than the last, which should
    allow dequeue to unblock a little earlier and helps
    make sure the previous buffer's release fence has
    been finalized before FenceTracker::addFrame is
    called.
* Fence tracker only sets the release fence once it
    has been finalized so it does not report a release
    fence for a buffer that is still latched.

Test: adb shell /data/nativetest/libgui_test/libgui_test
--gtest_filter=*GetFrameTimestamps*

Change-Id: I27d484bfd48f730bdcea2628f96795c6f4b4df7b
diff --git a/services/surfaceflinger/FenceTracker.cpp b/services/surfaceflinger/FenceTracker.cpp
index 742c00d..4dac0db 100644
--- a/services/surfaceflinger/FenceTracker.cpp
+++ b/services/surfaceflinger/FenceTracker.cpp
@@ -158,38 +158,17 @@
 
         layers[i]->getFenceData(&name, &frameNumber, &glesComposition,
                 &requestedPresentTime, &acquireFence, &prevReleaseFence);
-#ifdef USE_HWC2
-        if (glesComposition) {
-            frame.layers.emplace(std::piecewise_construct,
-                    std::forward_as_tuple(layerId),
-                    std::forward_as_tuple(name, frameNumber, glesComposition,
-                    requestedPresentTime, 0, 0, acquireFence,
-                    prevReleaseFence));
-            wasGlesCompositionDone = true;
-        } else {
-            frame.layers.emplace(std::piecewise_construct,
-                    std::forward_as_tuple(layerId),
-                    std::forward_as_tuple(name, frameNumber, glesComposition,
-                    requestedPresentTime, 0, 0, acquireFence, Fence::NO_FENCE));
-            auto prevLayer = prevFrame.layers.find(layerId);
-            if (prevLayer != prevFrame.layers.end()) {
-                prevLayer->second.releaseFence = prevReleaseFence;
+
+        frame.layers.emplace(std::piecewise_construct,
+                std::forward_as_tuple(layerId),
+                std::forward_as_tuple(name, frameNumber, glesComposition,
+                requestedPresentTime, 0, 0, acquireFence, Fence::NO_FENCE));
+        auto prevLayer = prevFrame.layers.find(layerId);
+        if (prevLayer != prevFrame.layers.end()) {
+            if (frameNumber != prevLayer->second.frameNumber) {
+               prevLayer->second.releaseFence = prevReleaseFence;
             }
         }
-#else
-        frame.layers.emplace(std::piecewise_construct,
-                std::forward_as_tuple(layerId),
-                std::forward_as_tuple(name, frameNumber, glesComposition,
-                requestedPresentTime, 0, 0, acquireFence,
-                glesComposition ? Fence::NO_FENCE : prevReleaseFence));
-        if (glesComposition) {
-            wasGlesCompositionDone = true;
-        }
-#endif
-        frame.layers.emplace(std::piecewise_construct,
-                std::forward_as_tuple(layerId),
-                std::forward_as_tuple(name, frameNumber, glesComposition,
-                requestedPresentTime, 0, 0, acquireFence, prevReleaseFence));
     }
 
     frame.frameId = mFrameCounter;