Add conversion constructor for hidl_string.
am: e03c08722d

Change-Id: Ib9756d5d390b1b41c1a1bee5659c7c24425a47a0
diff --git a/HidlSupport.cpp b/HidlSupport.cpp
index 98c235c..ed3e12e 100644
--- a/HidlSupport.cpp
+++ b/HidlSupport.cpp
@@ -37,6 +37,10 @@
     clear();
 }
 
+hidl_string::hidl_string(const char *s) : hidl_string() {
+    *this = s;
+}
+
 hidl_string::hidl_string(const hidl_string &other)
     : mBuffer(const_cast<char *>(kEmptyString)),
       mSize(0),
diff --git a/include/hidl/HidlSupport.h b/include/hidl/HidlSupport.h
index ec9123a..c3ec8f5 100644
--- a/include/hidl/HidlSupport.h
+++ b/include/hidl/HidlSupport.h
@@ -35,13 +35,15 @@
     ~hidl_string();
 
     hidl_string(const hidl_string &);
-    hidl_string &operator=(const hidl_string &);
+    hidl_string(const char *);
 
     const char *c_str() const;
     size_t size() const;
     bool empty() const;
 
+    hidl_string &operator=(const hidl_string &);
     hidl_string &operator=(const char *s);
+
     void clear();
 
     // Reference an external char array. Ownership is _not_ transferred.