add AidlVariableDeclaration::GetCapitalizedName()

to remove dup in aidl_language.cpp and generate_java.cpp.

Bug: n/a
Test: aidl_unittests
Change-Id: Ib4f9fae0a38c188f97d0d2cf9f47889e170fa784
diff --git a/aidl_language.h b/aidl_language.h
index dbd987e..7bc249b 100644
--- a/aidl_language.h
+++ b/aidl_language.h
@@ -347,6 +347,7 @@
   AidlVariableDeclaration& operator=(AidlVariableDeclaration&&) = delete;
 
   std::string GetName() const { return name_; }
+  std::string GetCapitalizedName() const;
   const AidlTypeSpecifier& GetType() const { return *type_; }
   // if this was constructed explicitly with a default value
   bool IsDefaultUserSpecified() const { return default_user_specified_; }