Merge "Always swap buffers if using partial update extension" into nyc-dev

libs/hwui/renderthread/CanvasContext.cpp

@@ -476,7 +476,7 @@ void CanvasContext::draw() {
     // metrics the frame was swapped at this point
     mCurrentFrameInfo->markSwapBuffers();
 
-    if (drew) {
+    if (drew || mEglManager.damageRequiresSwap()) {
         if (CC_UNLIKELY(!mEglManager.swapBuffers(frame, screenDirty))) {
             setSurface(nullptr);
         }

libs/hwui/renderthread/EglManager.cpp

@@ -324,6 +324,10 @@ void EglManager::damageFrame(const Frame& frame, const SkRect& dirty) {
 #endif
 }
 
+bool EglManager::damageRequiresSwap() {
+    return EglExtensions.setDamage && mSwapBehavior == SwapBehavior::BufferAge;
+}
+
 bool EglManager::swapBuffers(const Frame& frame, const SkRect& screenDirty) {
 
     if (CC_UNLIKELY(Properties::waitForGpuCompletion)) {

libs/hwui/renderthread/EglManager.h

@@ -70,6 +70,10 @@ public:
     bool makeCurrent(EGLSurface surface, EGLint* errOut = nullptr);
     Frame beginFrame(EGLSurface surface);
     void damageFrame(const Frame& frame, const SkRect& dirty);
+    // If this returns true it is mandatory that swapBuffers is called
+    // if damageFrame is called without subsequent calls to damageFrame().
+    // See EGL_KHR_partial_update for more information
+    bool damageRequiresSwap();
     bool swapBuffers(const Frame& frame, const SkRect& screenDirty);
 
     // Returns true iff the surface is now preserving buffers.