_http: Fix final doc comment issues

Change-Id: Ie1ed719aca9b1f18240b811271ac952818d04c89
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/218664
Auto-Submit: Kevin Moore <kevmoo@google.com>
Commit-Queue: Kevin Moore <kevmoo@google.com>
Commit-Queue: Devon Carew <devoncarew@google.com>
Reviewed-by: Devon Carew <devoncarew@google.com>

sdk/lib/_http/http.dart

@@ -1199,7 +1199,7 @@ abstract class HttpResponse implements IOSink {
 /// If a body is present, it must be read. Otherwise, it leads to resource
 /// leaks. Consider using [HttpClientResponse.drain] if the body is unused.
 ///
-/// ```dart
+/// ```dart import:convert
 /// var client = HttpClient();
 /// try {
 ///   HttpClientRequest request = await client.get('localhost', 80, '/file.txt');
@@ -1673,7 +1673,8 @@ abstract class HttpClient {
 /// encoding used is determined from the "charset" parameter of
 /// the "Content-Type" header.
 ///
-/// ```dart
+/// ```dart import:convert
+/// var client = HttpClient();
 /// HttpClientRequest request = await client.get('localhost', 80, '/file.txt');
 /// request.headers.contentType =
 ///     ContentType('application', 'json', charset: 'utf-8');
@@ -1683,6 +1684,7 @@ abstract class HttpClient {
 /// If no charset is provided the default of ISO-8859-1 (Latin 1) is used.
 ///
 /// ```dart
+/// var client = HttpClient();
 /// HttpClientRequest request = await client.get('localhost', 80, '/file.txt');
 /// request.headers.add(HttpHeaders.contentTypeHeader, "text/plain");
 /// request.write('blåbærgrød'); // Strings written will be ISO-8859-1 encoded
@@ -1783,8 +1785,9 @@ abstract class HttpClientRequest implements IOSink {
   /// the request has been aborted
   ///
   /// ```dart import:async
-  /// HttpClientRequest request = ...
-  /// request.write();
+  /// var client = HttpClient();
+  /// HttpClientRequest request = await client.get('localhost', 80, '/file.txt');
+  /// request.write('request content');
   /// Timer(Duration(seconds: 1), () {
   ///   request.abort();
   /// });
@@ -1804,7 +1807,7 @@ abstract class HttpClientRequest implements IOSink {
 /// server. Use [Stream] methods like [`transform`][Stream.transform] and
 /// [`join`][Stream.join] to access the data.
 ///
-/// ```dart
+/// ```dart import:convert
 /// var client = HttpClient();
 /// try {
 ///   HttpClientRequest request = await client.get('localhost', 80, '/file.txt');

sdk/lib/_http/overrides.dart

@@ -13,20 +13,22 @@ const _asyncRunZoned = runZoned;
 /// that construct a mock implementation. The implementation in this base class
 /// defaults to the actual [HttpClient] implementation. For example:
 ///
-/// ```dart
+/// ```dart import:io
+/// // An implementation of the HttpClient interface
 /// class MyHttpClient implements HttpClient {
-///   ...
-///   // An implementation of the HttpClient interface
-///   ...
+///   MyHttpClient(SecurityContext? c);
+///
+///   @override
+///   noSuchMethod(Invocation invocation) {
+///     // your implementation here
+///   }
 /// }
 ///
-/// main() {
+/// void main() {
 ///   HttpOverrides.runZoned(() {
-///     ...
 ///     // Operations will use MyHttpClient instead of the real HttpClient
 ///     // implementation whenever HttpClient is used.
-///     ...
-///   }, createHttpClient: (SecurityContext c) => MyHttpClient(c));
+///   }, createHttpClient: (SecurityContext? c) => MyHttpClient(c));
 /// }
 /// ```
 abstract class HttpOverrides {

tools/bots/test_matrix.json

@@ -3474,6 +3474,7 @@
           "script": "out/ReleaseX64/dart-sdk/bin/dart",
           "arguments": [
             "tools/verify_docs/bin/verify_docs.dart",
+            "sdk/lib/_http",
             "sdk/lib/_internal",
             "sdk/lib/cli",
             "sdk/lib/convert",