Add ArrayDataTraits<> specialization for Array_Data<T>*.

Currently, we use wrong storage type for nested arrays. For example, the storage
type of the outer array of int8[][] is
StructPointer<Array_Data<int8_t>>. After this CL it will be
ArrayPointer<int8_t>.

The current code works because StructPointer happens to be of the same
size as ArrayPointer.

(The newly-added tests pass with/without this CL. But I think it is good
to have them.)

BUG=None
TEST=None

Review URL: https://codereview.chromium.org/340223002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@278356 0039d316-1c4b-4281-b951-d872f2087c98

mojo/public/cpp/bindings/lib/array_internal.h

@@ -54,6 +54,23 @@ struct ArrayDataTraits<P*> {
   }
 };
 
+template <typename T>
+struct ArrayDataTraits<Array_Data<T>*> {
+  typedef ArrayPointer<T> StorageType;
+  typedef Array_Data<T>*& Ref;
+  typedef Array_Data<T>* const& ConstRef;
+
+  static size_t GetStorageSize(size_t num_elements) {
+    return sizeof(StorageType) * num_elements;
+  }
+  static Ref ToRef(StorageType* storage, size_t offset) {
+    return storage[offset].ptr;
+  }
+  static ConstRef ToConstRef(const StorageType* storage, size_t offset) {
+    return storage[offset].ptr;
+  }
+};
+
 // Specialization of Arrays for bools, optimized for space. It has the
 // following differences from a generalized Array:
 // * Each element takes up a single bit of memory.

mojo/public/interfaces/bindings/tests/data/validation/conformance_mthd6_good.data

+[dist4]message_header  // num_bytes
+[u4]2                  // num_fields
+[u4]6                  // name
+[u4]0                  // flags
+[anchr]message_header
+
+[dist4]method6_params  // num_bytes
+[u4]1                  // num_fields
+[dist8]param0_ptr      // param0
+[anchr]method6_params
+
+[anchr]param0_ptr
+[dist4]array_param  // num_bytes
+[u4]1               // num_elements
+[dist8]element_ptr
+[anchr]array_param
+
+[anchr]element_ptr
+[dist4]array_element  // num_bytes
+[u4]10                // num_elements
+0 1 2 3 4 5 6 7 8 9
+[anchr]array_element

mojo/public/interfaces/bindings/tests/data/validation/conformance_mthd6_good.expected

+PASS

mojo/public/interfaces/bindings/tests/data/validation/conformance_mthd6_nested_array_num_bytes_less_than_necessary_size.data

+[dist4]message_header  // num_bytes
+[u4]2                  // num_fields
+[u4]6                  // name
+[u4]0                  // flags
+[anchr]message_header
+
+[dist4]method6_params  // num_bytes
+[u4]1                  // num_fields
+[dist8]param0_ptr      // param0
+[anchr]method6_params
+
+[anchr]param0_ptr
+[dist4]array_param  // num_bytes
+[u4]1               // num_elements
+[dist8]element_ptr
+[anchr]array_param
+
+[anchr]element_ptr
+[dist4]array_element  // num_bytes: It is insufficient to store 12 elements.
+[u4]12                // num_elements
+0 1 2 3 4 5 6 7 8 9
+[anchr]array_element

mojo/public/interfaces/bindings/tests/data/validation/conformance_mthd6_nested_array_num_bytes_less_than_necessary_size.expected

+VALIDATION_ERROR_UNEXPECTED_ARRAY_HEADER

mojo/public/interfaces/bindings/tests/validation_test_interfaces.mojom

@@ -32,6 +32,7 @@ interface ConformanceTestInterface {
   Method3(bool[] param0);
   Method4(StructC param0, uint8[] param1);
   Method5(StructE param0, handle<data_pipe_producer> param1);
+  Method6(uint8[][] param0);
 };
 
 struct BasicStruct {