[milo] Refactor all html knowledge out of backends.

milo/frontend/view_builder.go

Index: milo/frontend/view_builder.go
diff --git a/milo/frontend/view_builder.go b/milo/frontend/view_builder.go
new file mode 100644
index 0000000000000000000000000000000000000000..901bbeebe2c4a5c9829cecd85fdb862eb06f69e3
--- /dev/null
+++ b/milo/frontend/view_builder.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"
+)
+
+// BuilderHandler is responsible for taking a universal builder ID and rendering
+// the builder page (defined in ./appengine/templates/pages/builder.html).
+func BuilderHandler(c *router.Context, builderID buildsource.BuilderID) {
+	builder, err := builderID.Get(c.Context, c.Params.ByName("limit"), c.Params.ByName("cursor"))
+	// 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/builder.html", templates.Args{
+			"Builder": builder,
+		})
+	}
+}