Refactor compile_aidl flow to support compiling C++

Bug: 23599760
Test: unittests

Change-Id: Id6cbe6ea8161be6ebf449e47b3934993e6b6ad13
diff --git a/options.cpp b/options.cpp
index 37c0638..620e9e0 100644
--- a/options.cpp
+++ b/options.cpp
@@ -23,6 +23,7 @@
 using std::endl;
 using std::string;
 using std::unique_ptr;
+using std::vector;
 
 namespace android {
 namespace aidl {
@@ -186,6 +187,10 @@
   return input_file_name_;
 }
 
+vector<string> CppOptions::ImportPaths() const {
+  return import_paths_;
+}
+
 unique_ptr<CppOptions> CppOptions::Parse(int argc, const char* const* argv) {
   unique_ptr<CppOptions> options(new CppOptions());
   int i = 1;