Mandoline: Support about:blank URL.

mojo/runner/about_fetcher.cc

Index: mojo/runner/about_fetcher.cc
diff --git a/mojo/runner/about_fetcher.cc b/mojo/runner/about_fetcher.cc
new file mode 100644
index 0000000000000000000000000000000000000000..e760a4c8cb7014a4d75a0d9dafa8d951e28b0a3f
--- /dev/null
+++ b/mojo/runner/about_fetcher.cc
@@ -0,0 +1,104 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "mojo/runner/about_fetcher.h"
+
+#include "base/bind.h"
+#include "base/files/file_path.h"
+#include "base/logging.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/message_loop/message_loop.h"
+#include "mojo/shell/data_pipe_peek.h"
+
+namespace mojo {
+namespace runner {
+namespace {
+
+void RunFetcherCallback(const shell::Fetcher::FetchCallback& callback,
+                        scoped_ptr<shell::Fetcher> fetcher,
+                        bool success) {
+  callback.Run(success ? fetcher.Pass() : nullptr);
+}
+
+}  // namespace
+
+const char AboutFetcher::kAboutScheme[] = "about";
+const char AboutFetcher::kAboutBlankURL[] = "about:blank";
+
+AboutFetcher::AboutFetcher(const GURL& url,
+                           const FetchCallback& loader_callback)
+    : Fetcher(loader_callback), url_(url) {
+  BuildResponse();
+}
+
+AboutFetcher::~AboutFetcher() {}
+
+void AboutFetcher::BuildResponse() {
+  if (url_ != GURL(kAboutBlankURL)) {
+    PostToRunCallback(false);
+    return;
+  }
+
+  response_ = URLResponse::New();
+  response_->url = kAboutBlankURL;
+  response_->status_code = 200;
+  response_->mime_type = "text/html";
+  PostToRunCallback(true);
+}
+
+void AboutFetcher::PostToRunCallback(bool success) {
+  // Also pass |this| on failure, so that we won't destroy the object while the
+  // constructor is still on the call stack.
+  base::MessageLoop::current()->PostTask(
+      FROM_HERE,
+      base::Bind(RunFetcherCallback, loader_callback_,
+                 base::Passed(make_scoped_ptr<Fetcher>(this)), success));
+}
+
+const GURL& AboutFetcher::GetURL() const {
+  return url_;
+}
+
+GURL AboutFetcher::GetRedirectURL() const {
+  return GURL::EmptyGURL();
+}
+
+GURL AboutFetcher::GetRedirectReferer() const {
+  return GURL::EmptyGURL();
+}
+
+URLResponsePtr AboutFetcher::AsURLResponse(base::TaskRunner* task_runner,
+                                           uint32_t skip) {
+  if (skip != 0 && response_->body.is_valid()) {

[sky, 2015/08/04 20:04:55]

Don't you need to make sure response_ is valid? AFAICT you never set body, is it
ever valid?

[yzshen1, 2015/08/05 16:11:08]

If |response_| is not valid, this object won't be passed to |loader_callback_|,
according to the Fetcher interface definition.
So nobody should access this method in that case.
You are right. Body is never set for about:blank.
I was thinking we will probably support more about: URLs than just about:blank
in this future, so this if-block could be useful.

What do you think? I could remove the whole if-block if that makes more sense.
Thanks!

[sky, 2015/08/05 17:35:49]

How about a DCHECK then.
I would rather you wait until body is set. Until then this code is useless.

[yzshen1, 2015/08/05 18:00:27]

Done.

+    MojoResult result = ReadDataRaw(
+        response_->body.get(), nullptr, &skip,
+        MOJO_READ_DATA_FLAG_ALL_OR_NONE | MOJO_READ_DATA_FLAG_DISCARD);
+    DCHECK_EQ(result, MOJO_RESULT_OK);
+  }
+  return response_.Pass();
+}
+
+void AboutFetcher::AsPath(
+    base::TaskRunner* task_runner,
+    base::Callback<void(const base::FilePath&, bool)> callback) {
+  NOTIMPLEMENTED();
+  base::MessageLoop::current()->PostTask(
+      FROM_HERE, base::Bind(callback, base::FilePath(), false));
+}
+
+std::string AboutFetcher::MimeType() {
+  return response_->mime_type;

[sky, 2015/08/04 20:04:55]

Check response?

[yzshen1, 2015/08/05 16:11:08]

Please see my previous comment.

+}
+
+bool AboutFetcher::HasMojoMagic() {
+  return false;
+}
+
+bool AboutFetcher::PeekFirstLine(std::string* line) {
+  return shell::BlockingPeekLine(response_->body.get(), line, kMaxShebangLength,

[sky, 2015/08/04 20:04:55]

Similar comments to that of AsURLResponse.

[yzshen1, 2015/08/05 16:11:08]

Please see my previous comment.

+                                 MOJO_DEADLINE_INDEFINITE);
+}
+
+}  // namespace runner
+}  // namespace mojo