Preload PNaCl plugin when the webapp is started.

remoting/webapp/client_plugin.js

Index: remoting/webapp/client_plugin.js
diff --git a/remoting/webapp/client_plugin.js b/remoting/webapp/client_plugin.js
index 181abcc83e5800433af723d752f46e6acd1cc128..076de9e44f7be8d8ab2d88da9d0e1d8daefbb0f0 100644
--- a/remoting/webapp/client_plugin.js
+++ b/remoting/webapp/client_plugin.js
@@ -24,24 +24,8 @@ var remoting = remoting || {};
  * @constructor
  */
 remoting.ClientPlugin = function(container, onExtensionMessage) {
-  this.plugin_ = /** @type {remoting.ViewerPlugin} */
-      document.createElement('embed');
-
+  this.plugin_ = remoting.ClientPlugin.createPluginElement_();
   this.plugin_.id = 'session-client-plugin';
-  if (remoting.settings.CLIENT_PLUGIN_TYPE == 'pnacl') {
-    this.plugin_.src = 'remoting_client_pnacl.nmf';
-    this.plugin_.type = 'application/x-pnacl';
-  } else if (remoting.settings.CLIENT_PLUGIN_TYPE == 'nacl') {
-    this.plugin_.src = 'remoting_client_nacl.nmf';
-    this.plugin_.type = 'application/x-nacl';
-  } else {
-    this.plugin_.src = 'about://none';
-    this.plugin_.type = 'application/vnd.chromium.remoting-viewer';
-  }
-
-  this.plugin_.width = 0;
-  this.plugin_.height = 0;
-  this.plugin_.tabIndex = 0;  // Required, otherwise focus() doesn't work.
   container.appendChild(this.plugin_);
 
   this.onExtensionMessage_ = onExtensionMessage;
@@ -116,6 +100,41 @@ remoting.ClientPlugin = function(container, onExtensionMessage) {
 };
 
 /**
+ * Creates plugin element without adding it to a container.
+ *
+ * @return {remoting.ViewerPlugin} Plugin element
+ */
+remoting.ClientPlugin.createPluginElement_ = function() {
+  var plugin = /** @type {remoting.ViewerPlugin} */
+      document.createElement('embed');
+  if (remoting.settings.CLIENT_PLUGIN_TYPE == 'pnacl') {
+    plugin.src = 'remoting_client_pnacl.nmf';
+    plugin.type = 'application/x-pnacl';
+  } else if (remoting.settings.CLIENT_PLUGIN_TYPE == 'nacl') {
+    plugin.src = 'remoting_client_nacl.nmf';
+    plugin.type = 'application/x-nacl';
+  } else {
+    plugin.src = 'about://none';
+    plugin.type = 'application/vnd.chromium.remoting-viewer';
+  }
+  plugin.width = 0;
+  plugin.height = 0;
+  plugin.tabIndex = 0;  // Required, otherwise focus() doesn't work.
+  return plugin;
+}
+
+/**
+ * Preloads the plugin to make instantiation faster when the user tries
+ * to connect.
+ */
+remoting.ClientPlugin.preload = function() {
+  if (remoting.settings.CLIENT_PLUGIN_TYPE != 'pnacl')
+    return;
+
+  document.body.appendChild(remoting.ClientPlugin.createPluginElement_());

[Wez, 2014/08/12 22:03:31]

Do we need to make sure the plugin is hidden?

[Jamie, 2014/08/12 22:35:58]

We'll end up with 2 plugins; is that okay? It might be cleaner to set an onLoad
handler on the element (or some other mechanism of determining when it's ready).
The handler would delete the element, and we shouldn't create the real plugin
until the pre-load one is deleted. WDYT?

[Jamie, 2014/08/12 22:35:58]

It mustn't have the hidden attribute set, or Chrome won't load it. We create it
0x0 instead.

[Sergey Ulanov, 2014/08/15 01:00:17]

Yes, the plugin handles multiple instances just fine.
It's not really necessary to block the creation of the real instance on the
preloading one - they should not interfere with each other. If user tries to
connect while chrome still compiles the plugin then chrome will wait until it's
compiled before it creates actual plugin instances (both instances will run in
the same process). I've added loadend even handled that deletes the plugin after
it's loaded. It doesn't look like it's worth keeping it around to use it later -
that would increase complexity here without much benefit (and we still need to
reset the plugin, e.g. for repeated connections).

+}
+
+/**
  * Set of features for which hasFeature() can be used to test.
  *
  * @enum {string}