Use #attached to add all CSS and JS

The plan is to use the logic in the cache plugins to find all the changed css/js put it into the global view object
and use it on to return a really simple render-array with #attached on it.

The problem with this though it that you need to use a cache plugin
even you actually don't use one because the block cache is active.

So maybe we should better move the logic into the display/view or create a stub cache-plugin.

Patch attached, retrieves css and js from cache plugin, and add them as #attached to the block content.

+++ b/lib/Drupal/views/Plugin/views/display/Block.phpundefined
@@ -68,7 +68,36 @@ class Block extends DisplayPluginBase {
+    $plugin_cache = $this->get_plugin('cache');
+    if (!$plugin_cache->cache_get('output')) {
+      $plugin_cache->gather_headers();

The cache is stored as a static cache on the display, so this code really gives you the information needed, just checked that.

+++ b/lib/Drupal/views/Plugin/views/display/Block.phpundefined
@@ -68,7 +68,36 @@ class Block extends DisplayPluginBase {
+    $attached = array(
+      'css' => $plugin_cache->storage['css'],
+      'js' => array(),
+    );
+
+    foreach ($plugin_cache->storage['js'] as $key => $args) {
+      if ($key !== 'settings') {
+        $attached['js'][] = $args;
+      }
+      else {
+        foreach ($args as $setting) {
+          $attached['js'][] = array(
+            'data' => $setting,
+            'type' => 'setting',
+          );
+        }
+      }

I'm wondering whether this code can be simplified by get something more usefull from the cache plugin.

Only thing I can see in term of simplification is avoiding the unnecessary iteration on files elements for js, as per attached patch.
One other solution could probably be to refactor CachePluginBase to set the $storage (and get_cache/set_cache) using an array(data, type) style, but seems quite an overhead as only settings won't be default "files" type.
Any other idea ?

+++ b/lib/Drupal/views/Plugin/views/display/Block.phpundefined
@@ -191,7 +216,7 @@ class Block extends DisplayPluginBase {
+        $this->save_block_cache($form_state['view']->name . '-' . $form_state['display_id'], $form_state['values']['block_caching']);
         break;
     }
   }
@@ -199,12 +224,12 @@ class Block extends DisplayPluginBase {

@@ -199,12 +224,12 @@ class Block extends DisplayPluginBase {
   /**
    * Block views use exposed widgets only if AJAX is set.
    */
-    function uses_exposed() {
-      if ($this->isAJAXEnabled()) {
-        return parent::uses_exposed();
-      }
-      return FALSE;
+  function uses_exposed() {
+    if ($this->isAJAXEnabled()) {
+      return parent::uses_exposed();
     }
+    return FALSE;
+  }
 
   /**
    * Update the block delta when you change the machine readable name of the display.
@@ -247,10 +272,10 @@ class Block extends DisplayPluginBase {

@@ -247,10 +272,10 @@ class Block extends DisplayPluginBase {
       $delta = md5($delta);
     }
     if (db_table_exists('block') && $bid = db_query("SELECT bid FROM {block} WHERE module = 'views' AND delta = :delta", array(
-        ':delta' => $delta))->fetchField()) {
+      ':delta' => $delta))->fetchField()) {
       db_update('block')
         ->fields(array(
-        'cache' => $cache_setting,
+          'cache' => $cache_setting,

As this will break some other patches please try to stay in the scope of the issue.

Removed the "noise", hadn't spotted this had went in, sorry. Deleted code is only one line, as css/js were not added there at all prior to this.

#8: 1748164-use_attached_for_block_js_css-8.patch queued for re-testing.

Looks like modern work is at #1811828: Use #attached to find the css/js of a view

I think it would help to backport.