Plugin Power Saver: Implement srcset syntax for posters.

chrome/renderer/plugins/chrome_plugin_placeholder.cc

Index: chrome/renderer/plugins/chrome_plugin_placeholder.cc
diff --git a/chrome/renderer/plugins/chrome_plugin_placeholder.cc b/chrome/renderer/plugins/chrome_plugin_placeholder.cc
index 375c3da5e934246d9157761de07e99cb7c93cd51..78c69202c367092f6e3dbe24eac93b2ca8af7fe8 100644
--- a/chrome/renderer/plugins/chrome_plugin_placeholder.cc
+++ b/chrome/renderer/plugins/chrome_plugin_placeholder.cc
@@ -56,12 +56,13 @@ ChromePluginPlaceholder::ChromePluginPlaceholder(
     blink::WebLocalFrame* frame,
     const blink::WebPluginParams& params,
     const std::string& html_data,
-    const base::string16& title)
+    const base::string16& title,
+    const GURL& placeholder_url)
     : plugins::LoadablePluginPlaceholder(render_frame,
                                          frame,
                                          params,
                                          html_data,
-                                         GURL(kPluginPlaceholderDataURL)),
+                                         placeholder_url),
       status_(new ChromeViewHostMsg_GetPluginInfo_Status),
       title_(title),
 #if defined(ENABLE_PLUGIN_INSTALLATION)
@@ -109,7 +110,8 @@ ChromePluginPlaceholder* ChromePluginPlaceholder::CreateMissingPlugin(
 
   // |missing_plugin| will destroy itself when its WebViewPlugin is going away.
   ChromePluginPlaceholder* missing_plugin = new ChromePluginPlaceholder(
-      render_frame, frame, params, html_data, params.mimeType);
+      render_frame, frame, params, html_data, params.mimeType,
+      GURL(kPluginPlaceholderDataURL));
   missing_plugin->set_allow_loading(true);
 #if defined(ENABLE_PLUGIN_INSTALLATION)
   RenderThread::Get()->Send(
@@ -136,7 +138,8 @@ ChromePluginPlaceholder* ChromePluginPlaceholder::CreateErrorPlugin(
   WebPluginParams params;
   // |missing_plugin| will destroy itself when its WebViewPlugin is going away.
   ChromePluginPlaceholder* plugin = new ChromePluginPlaceholder(
-      render_frame, NULL, params, html_data, params.mimeType);
+      render_frame, NULL, params, html_data, params.mimeType,
+      GURL(kPluginPlaceholderDataURL));
 
   RenderThread::Get()->Send(new ChromeViewHostMsg_CouldNotLoadPlugin(
       plugin->routing_id(), file_path));
@@ -153,14 +156,15 @@ ChromePluginPlaceholder* ChromePluginPlaceholder::CreateBlockedPlugin(
     const base::string16& name,
     int template_id,
     const base::string16& message,
-    const GURL& poster_url) {
+    const std::string& poster_attribute,
+    const GURL& placeholder_url) {
   base::DictionaryValue values;
   values.SetString("message", message);
   values.SetString("name", name);
   values.SetString("hide", l10n_util::GetStringUTF8(IDS_PLUGIN_HIDE));
 
-  if (poster_url.is_valid())
-    values.SetString("background", "url('" + poster_url.spec() + "')");
+  if (!poster_attribute.empty())
+    values.SetString("poster", poster_attribute);
 
   const base::StringPiece template_html(
       ResourceBundle::GetSharedInstance().GetRawDataResource(template_id));
@@ -171,10 +175,12 @@ ChromePluginPlaceholder* ChromePluginPlaceholder::CreateBlockedPlugin(
 
   // |blocked_plugin| will destroy itself when its WebViewPlugin is going away.
   ChromePluginPlaceholder* blocked_plugin = new ChromePluginPlaceholder(
-      render_frame, frame, params, html_data, name);
+      render_frame, frame, params, html_data, name,
+      placeholder_url.is_valid() ? placeholder_url

[tommycli, 2015/03/04 19:55:17]

Needs some security scrutiny:

In order to allow resolving of relative paths, we set the placeholder's URL to
the document URL instead of data:text/html,pluginplaceholderdata.

Is this safe? I could not think of another reasonable alternative to doing this.

Previously, we resolved the image to an absolute path before passing it into
here. Now, we are switching to the img srcset syntax, i.e. <img
srcset="poster1x.png 1x, poster2x.png 2x">.

The srcset parsing code is deep and nonpublic in Blink, so it would be a real
PITA to resolve them to absolute paths.

[Bernhard Bauer, 2015/03/05 09:12:51]

Could you just set a <base> tag in the header? That would allow resolving
relative URLs, without changing security-related properties (AFAIK).

[tommycli, 2015/03/05 19:49:12]

That totally worked! You guys are smarter than me!

+                                 : GURL(kPluginPlaceholderDataURL));
 
 #if defined(ENABLE_PLUGINS)
-  if (poster_url.is_valid())
+  if (!poster_attribute.empty())
     blocked_plugin->BlockForPowerSaverPoster();
 #endif
   blocked_plugin->SetPluginInfo(info);