[milo] Refactor all html knowledge out of backends.

milo/frontend/view_build.go

Index: milo/frontend/view_build.go
diff --git a/milo/frontend/view_build.go b/milo/frontend/view_build.go
new file mode 100644
index 0000000000000000000000000000000000000000..8f8e188d40981e0e7969dd6b6db9c63319d064d4
--- /dev/null
+++ b/milo/frontend/view_build.go
@@ -0,0 +1,27 @@
+// Copyright 2017 The LUCI Authors. All rights reserved.
+// Use of this source code is governed under the Apache License, Version 2.0
+// that can be found in the LICENSE file.
+
+package frontend
+
+import (
+	"github.com/luci/luci-go/milo/buildsource"
+	"github.com/luci/luci-go/server/router"
+	"github.com/luci/luci-go/server/templates"
+)
+
+// BuildHandler is responsible for taking a universal build ID and rendering the
+// build page (defined in ./appengine/templates/pages/build.html).
+func BuildHandler(c *router.Context, buildID buildsource.ID) {
+	build, err := buildID.Get(c.Context)
+	// TODO(iannucci, hinoka): make MiloBuild refer to annotation stream by
+	// host/prefix/path instead of by directly pulling it. Do all annotation
+	// stream rendering in the frontend.
+	if err != nil {
+		ErrorHandler(c, err)
+	} else {
+		templates.MustRender(c.Context, c.Writer, "pages/build.html", templates.Args{
+			"Build": build,
+		})
+	}
+}