upload android base code part6

android/system/tools/aidl/docs/constants.md

@@ -0,0 +1,35 @@
+# Defining constants as part of an interface
+
+AIDL has been enhanced to support defining integer and string constants
+as part of an interface.
+
+## Integer constants
+
+```
+interface IMyInterface {
+    const int CONST_A = 1;
+    const int CONST_B = 2;
+    const int CONST_C = 3;
+    ...
+}
+```
+
+These map to appropriate 32 bit integer class constants in Java and C++ (e.g.
+`IMyInterface.CONST_A` and `IMyInterface::CONST_A` respectively).
+
+## String constants
+
+```
+interface IMyInterface {
+    const String CONST_A = "foo";
+    const String CONST_B = "bar";
+    ...
+}
+```
+
+These map to class level String constants in Java, and static getter
+functions that return a const android::String16& in C++.
+
+The constants are limited to contain printable ASCII characters < 0x10
+and without backspaces (i.e. no '\' character).
+