pw_tls_client_mbedtls: Initial commit

Add docs and some placeholder data strucutre types to be implemented
later.

Bug: 398
Change-Id: Ib6b1f2cc7ee51218e174f6b645d983ed551d87c7
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/50460
Commit-Queue: Yecheng Zhao <zyecheng@google.com>
Reviewed-by: Ali Zhang <alizhang@google.com>
diff --git a/pw_tls_client_mbedtls/BUILD.gn b/pw_tls_client_mbedtls/BUILD.gn
new file mode 100644
index 0000000..db41c2f
--- /dev/null
+++ b/pw_tls_client_mbedtls/BUILD.gn
@@ -0,0 +1,47 @@
+# Copyright 2021 The Pigweed Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may not
+# use this file except in compliance with the License. You may obtain a copy of
+# the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations under
+# the License.
+
+import("//build_overrides/pigweed.gni")
+import("$dir_pw_build/facade.gni")
+import("$dir_pw_build/target_types.gni")
+import("$dir_pw_docgen/docs.gni")
+
+config("public_includes") {
+  include_dirs = [ "public" ]
+}
+
+config("overrides") {
+  include_dirs = [ "public_overrides" ]
+}
+
+pw_source_set("pw_tls_client_mbedtls") {
+  public_configs = [
+    ":public_includes",
+    ":overrides",
+  ]
+  public = [
+    "public/pw_tls_client_mbedtls/backend_types.h",
+    "public_overrides/pw_tls_client_backends/backend_types.h",
+  ]
+  sources = [ "tls_client_mbedtls.cc" ]
+  public_deps = [
+    "$dir_pigweed/pw_tls_client:pw_tls_client.facade",
+    "$dir_pw_tls_client:tls_entropy",
+    "//third_party/mbedtls",
+  ]
+}
+
+pw_doc_group("docs") {
+  sources = [ "docs.rst" ]
+}