Add app engine app to mirror html docs from chromium.googlesource.com

doc/appengine/main.go

+// Copyright 2015 The Crashpad Authors. All rights reserved.
+//
+// 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
+//
+//     http://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.
+
+// Package crashpad mirrors crashpad documentation from Chromium’s git repo.
+package crashpad
+
+import (
+        "io"
+        "net/http"
+        "path"
+        "strings"
+
+        "google.golang.org/appengine"
+        "google.golang.org/appengine/urlfetch"
+)
+
+const baseURL = "http://docs.crashpad.googlecode.com/git"
+
+func init() {
+        http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+                ctx := appengine.NewContext(r)
+                client := urlfetch.Client(ctx)
+
+                // Don’t show dotfiles.
+                if strings.HasPrefix(path.Base(r.URL.Path), ".") {
+                        http.Error(w, http.StatusText(http.StatusNotFound), http.StatusNotFound)
+                        return
+                }
+
+                if r.URL.Path == "/" {
+                        http.Redirect(w, r, "/index.html", http.StatusFound)
+                        return
+                }
+
+                resp, err := client.Get(baseURL + r.URL.Path)
+                if err != nil {
+                        http.Error(w, err.Error(), http.StatusInternalServerError)
+                        return
+                }
+                defer resp.Body.Close()
+                w.Header().Set("Content-Type", resp.Header.Get("Content-Type"))

[Mark Mentovai, 2015/10/08 19:07:09]

We have .html, .css, .js, and .png. Does this set the right Content-Type for all
of these?

+                io.Copy(w, resp.Body)
+        })
+}