gralloc1: Fixes for hidl

* Fix capabilities check
* Use unique ID for backing store per the hidl spec

CRs-Fixed: 2009826
Change-Id: Ifc2be98a00dc3b0e4fd4e3e4c8d343de6afd8560
diff --git a/libgralloc1/gr_device_impl.cpp b/libgralloc1/gr_device_impl.cpp
index 121d0cf..2bb66d1 100644
--- a/libgralloc1/gr_device_impl.cpp
+++ b/libgralloc1/gr_device_impl.cpp
@@ -100,16 +100,13 @@
 }
 
 void GrallocImpl::GetCapabilities(struct gralloc1_device *device, uint32_t *out_count,
-                                  int32_t /*gralloc1_capability_t*/ *out_capabilities) {
-  if (!device) {
-    // Need to plan for adding more capabilities
-    if (out_capabilities == NULL) {
-      *out_count = 1;
-    } else {
-      *out_capabilities = GRALLOC1_CAPABILITY_TEST_ALLOCATE;
+                                  int32_t  /*gralloc1_capability_t*/ *out_capabilities) {
+  if (device != nullptr) {
+    if (out_capabilities != nullptr && *out_count > 0) {
+      out_capabilities[0] = GRALLOC1_CAPABILITY_TEST_ALLOCATE;
     }
+    *out_count = 1;
   }
-
   return;
 }
 
diff --git a/libgralloc1/gr_priv_handle.h b/libgralloc1/gr_priv_handle.h
index 61190c2..9a7e7b6 100644
--- a/libgralloc1/gr_priv_handle.h
+++ b/libgralloc1/gr_priv_handle.h
@@ -175,7 +175,7 @@
 
   gralloc1_producer_usage_t GetProducerUsage() const { return producer_usage; }
 
-  int GetBackingstore() const { return fd; }
+  uint64_t GetBackingstore() const { return id; }
 };
 
 #endif  // __GR_PRIV_HANDLE_H__