Revert "Revert "Bind to FBO when using GPU composition""

Hold for now while I propose a fix on top of this change.

This reverts commit 8d4f90aaadf9f3be77d258d2acd67b6186352811.

Reason for revert: Forward fixing

Bug: 117680609
Change-Id: I68a26ced146fa057de3aeb144cbfe2fa3c9842fe
Test: See If639ce2c6cd600eabb957d278815f80b413d92b3
diff --git a/services/surfaceflinger/DisplayDevice.h b/services/surfaceflinger/DisplayDevice.h
index bcd3330..560a958 100644
--- a/services/surfaceflinger/DisplayDevice.h
+++ b/services/surfaceflinger/DisplayDevice.h
@@ -28,13 +28,14 @@
 #include <gui/LayerState.h>
 #include <hardware/hwcomposer_defs.h>
 #include <math/mat4.h>
+#include <renderengine/RenderEngine.h>
 #include <renderengine/Surface.h>
 #include <ui/GraphicTypes.h>
 #include <ui/HdrCapabilities.h>
 #include <ui/Region.h>
 #include <ui/Transform.h>
-#include <utils/RefBase.h>
 #include <utils/Mutex.h>
+#include <utils/RefBase.h>
 #include <utils/String8.h>
 #include <utils/Timers.h>
 
@@ -146,10 +147,13 @@
                           ui::Dataspace* outDataspace, ui::ColorMode* outMode,
                           ui::RenderIntent* outIntent) const;
 
-    void swapBuffers(HWComposer& hwc) const;
+    // Queues the drawn buffer for consumption by HWC.
+    void queueBuffer(HWComposer& hwc);
+    // Allocates a buffer as scratch space for GPU composition
+    sp<GraphicBuffer> dequeueBuffer();
 
     // called after h/w composer has completed its set() call
-    void onSwapBuffersCompleted() const;
+    void onPresentDisplayCompleted();
 
     Rect getBounds() const {
         return Rect(mDisplayWidth, mDisplayHeight);
@@ -160,6 +164,11 @@
     const std::string& getDisplayName() const { return mDisplayName; }
 
     bool makeCurrent() const;
+    // Acquires a new buffer for GPU composition.
+    void readyNewBuffer();
+    // Marks the current buffer has finished, so that it can be presented and
+    // swapped out.
+    void finishBuffer();
     void setViewportAndProjection() const;
 
     const sp<Fence>& getClientTargetAcquireFence() const;
@@ -204,7 +213,12 @@
 
     // ANativeWindow this display is rendering into
     sp<ANativeWindow> mNativeWindow;
+    // Current buffer that this display can render to.
+    sp<GraphicBuffer> mGraphicBuffer;
     sp<DisplaySurface> mDisplaySurface;
+    // File descriptor indicating that mGraphicBuffer is ready for display, i.e.
+    // that drawing to the buffer is now complete.
+    base::unique_fd mBufferReady;
 
     std::unique_ptr<renderengine::Surface> mSurface;
     int             mDisplayWidth;