Add Page-Title header to tree and blob JSON endpoints

app/controllers/application_controller.rb

@@ -25,6 +25,8 @@ class ApplicationController < ActionController::Base
   around_action :set_locale
+  after_action :set_page_title_header, if: -> { request.format == :json }
+
   protect_from_forgery with: :exception
   helper_method :can?, :current_application_settings
@@ -335,4 +337,8 @@ class ApplicationController < ActionController::Base
       sign_in user, store: false
     end
   end
+
+  def set_page_title_header
+    response.headers['Page-Title'] = page_title('GitLab')
+  end
 end

app/controllers/projects/blob_controller.rb

@@ -41,6 +41,8 @@ class Projects::BlobController < Projects::ApplicationController
       end
       format.json do
+        page_title @blob.path, @ref, @project.name_with_namespace
+
         show_json
       end
     end

app/controllers/projects/tree_controller.rb

@@ -35,6 +35,8 @@ class Projects::TreeController < Projects::ApplicationController
       end
       format.json do
+        page_title @path.presence || _("Files"), @ref, @project.name_with_namespace
+
         # n+1: https://gitlab.com/gitlab-org/gitlab-ce/issues/38261
         Gitlab::GitalyClient.allow_n_plus_1_calls do
           render json: TreeSerializer.new(project: @project, repository: @repository, ref: @ref).represent(@tree)

app/helpers/page_layout_helper.rb

@@ -9,7 +9,7 @@ module PageLayoutHelper
     end
     # Segments are seperated by middot
-    @page_title.join(" \u00b7 ")
+    @page_title.join(" · ")
   end
   # Define or get a description for the current page