libui: use unique_fd in Fence

Use unique_fd internally.  Add a constructor to create a Fence from
a unique_fd.

Test: boots
Change-Id: I36e7a337885a6559ed6fe82c56b718f56108aaf8
diff --git a/libs/ui/Fence.cpp b/libs/ui/Fence.cpp
index b67f4d9..ff53aa8 100644
--- a/libs/ui/Fence.cpp
+++ b/libs/ui/Fence.cpp
@@ -37,18 +37,12 @@
 
 const sp<Fence> Fence::NO_FENCE = sp<Fence>(new Fence);
 
-Fence::Fence() :
-    mFenceFd(-1) {
-}
-
 Fence::Fence(int fenceFd) :
     mFenceFd(fenceFd) {
 }
 
-Fence::~Fence() {
-    if (mFenceFd != -1) {
-        close(mFenceFd);
-    }
+Fence::Fence(base::unique_fd fenceFd) :
+    mFenceFd(std::move(fenceFd)) {
 }
 
 status_t Fence::wait(int timeout) {
@@ -68,7 +62,7 @@
     int warningTimeout = 3000;
     int err = sync_wait(mFenceFd, warningTimeout);
     if (err < 0 && errno == ETIME) {
-        ALOGE("%s: fence %d didn't signal in %u ms", logname, mFenceFd,
+        ALOGE("%s: fence %d didn't signal in %u ms", logname, mFenceFd.get(),
                 warningTimeout);
         err = sync_wait(mFenceFd, TIMEOUT_NEVER);
     }
@@ -94,7 +88,7 @@
     if (result == -1) {
         status_t err = -errno;
         ALOGE("merge: sync_merge(\"%s\", %d, %d) returned an error: %s (%d)",
-                name, f1->mFenceFd, f2->mFenceFd,
+                name, f1->mFenceFd.get(), f2->mFenceFd.get(),
                 strerror(-err), err);
         return NO_FENCE;
     }
@@ -117,7 +111,7 @@
 
     struct sync_fence_info_data* finfo = sync_fence_info(mFenceFd);
     if (finfo == NULL) {
-        ALOGE("sync_fence_info returned NULL for fd %d", mFenceFd);
+        ALOGE("sync_fence_info returned NULL for fd %d", mFenceFd.get());
         return SIGNAL_TIME_INVALID;
     }
     if (finfo->status != 1) {
@@ -181,7 +175,7 @@
     }
 
     if (numFds) {
-        mFenceFd = *fds++;
+        mFenceFd.reset(*fds++);
         count--;
     }