Fix google-explicit-constructor warnings.

Bug: 28341362
Change-Id: I0ce850de85e0de6a5472dd142f738856142db9ec
diff --git a/libs/binder/IMemory.cpp b/libs/binder/IMemory.cpp
index e9891a8..f27b882 100644
--- a/libs/binder/IMemory.cpp
+++ b/libs/binder/IMemory.cpp
@@ -74,7 +74,7 @@
 class BpMemoryHeap : public BpInterface<IMemoryHeap>
 {
 public:
-    BpMemoryHeap(const sp<IBinder>& impl);
+    explicit BpMemoryHeap(const sp<IBinder>& impl);
     virtual ~BpMemoryHeap();
 
     virtual int getHeapID() const;
@@ -122,7 +122,7 @@
 class BpMemory : public BpInterface<IMemory>
 {
 public:
-    BpMemory(const sp<IBinder>& impl);
+    explicit BpMemory(const sp<IBinder>& impl);
     virtual ~BpMemory();
     virtual sp<IMemoryHeap> getMemory(ssize_t* offset=0, size_t* size=0) const;