Added google_analytics so it can be inserted into handlebars

src/book/mod.rs

@@ -36,6 +36,8 @@ pub struct MDBook {
     /// Should `mdbook build` create files referenced from SUMMARY.md if they
     /// don't exist
     pub create_missing: bool,
+
+    pub google_analytics: Option<String>,
 }
 
 impl MDBook {
@@ -84,6 +86,7 @@ impl MDBook {
 
             livereload: None,
             create_missing: true,
+            google_analytics: None,
         }
     }
 

src/renderer/html_handlebars/hbs_renderer.rs

@@ -194,7 +194,9 @@ fn make_data(book: &MDBook) -> Result<serde_json::Map<String, serde_json::Value>
     }
 
     // Add google analytics tag
-    data.insert("google_analytics".to_owned(), json!("INSERT_GA_ID_HERE"));
+    if let Some(ref ga) = book.google_analytics {
+        data.insert("google_analytics".to_owned(), json!(ga));
+    }
 
     let mut chapters = vec![];