Add message for Empty Repositories

The empty repository experience can be confusing, as there is nothing
rendered at all. This leads users to wonder if there was a problem
rendering or if the repository is truly empty. This change adds a message
that is shown to the user in the event that there are no log, branches, nor
tags in the repository.

Change-Id: I204b5f6090a7750d2ca89e5c36c1661fc3a3ddba

resources/com/google/gitiles/static/base.css

diff --git a/resources/com/google/gitiles/static/base.css b/resources/com/google/gitiles/static/base.css
index 2a56084..37a98c4 100644
--- a/resources/com/google/gitiles/static/base.css
+++ b/resources/com/google/gitiles/static/base.css
@@ -282,6 +282,11 @@
   margin-top: 20px;
   padding-top: 5px;
 }
+.EmptyRepo-header {}
+.EmptyRepo-description {
+  font-size: 14px;
+  font-style: italic;
+}
 
 /* RefList.soy */
 

resources/com/google/gitiles/templates/RepositoryIndex.soy

diff --git a/resources/com/google/gitiles/templates/RepositoryIndex.soy b/resources/com/google/gitiles/templates/RepositoryIndex.soy
index b3178e4..af1af50 100644
--- a/resources/com/google/gitiles/templates/RepositoryIndex.soy
+++ b/resources/com/google/gitiles/templates/RepositoryIndex.soy
@@ -88,6 +88,9 @@
 {elseif length($branches) or length($tags)}
   {call .branches_ data="all" /}
   {call .tags_ data="all" /}
+{else}
+  <h1 class="EmptyRepo-header">Empty Repository</h1>
+  <p class="EmptyRepo-description">This repository is empty. Push to it to show branches and history.</p>
 {/if}
 
 {call .footer}