SF: Clean framebuffer cache on hotplug

This CL cleans the framebuffer cache when a hotplug event
for already connected display is processed. This way when we
destruct the DisplayDevice the framebuffers will be completely
deallocated, so they can later be reallocated.

Test: 1. unplug HDMI
      2. adb shell dumpsys SurfaceFlinger | grep FramebufferSurface
         verify only 3 framebuffers are allocated
      3. plug HDMI
      5. adb shell dumpsys SurfaceFlinger | grep FramebufferSurface
         verify only 3 framebuffers are allocated
Test: Using dev SurfaceFlinger backdoor (1036) which injects hotplug:
      adb shell service call SurfaceFlinger 1036 && \
        adb shell dumpsys SurfaceFlinger | grep FramebufferSurface
Bug: 160112047
Bug: 167670568
Change-Id: I96282bec439ebf413dcd5d57f6b884eccef19c5f

1 files changed, 1 insertions, 0 deletions

diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 6478497b8f..9d35a3fca6 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -2684,6 +2684,7 @@ void SurfaceFlinger::processDisplayChanged(const wp<IBinder>& displayToken,
     const sp<IBinder> drawingBinder = IInterface::asBinder(drawingState.surface);
     if (currentBinder != drawingBinder || currentState.sequenceId != drawingState.sequenceId) {
         // changing the surface is like destroying and recreating the DisplayDevice
+        getRenderEngine().cleanFramebufferCache();
         if (const auto display = getDisplayDeviceLocked(displayToken)) {
             display->disconnect();
         }