Plugin Power Saver: Restrict Power Saver to cross-origin.

content/renderer/pepper/pepper_plugin_instance_impl.cc

Index: content/renderer/pepper/pepper_plugin_instance_impl.cc
diff --git a/content/renderer/pepper/pepper_plugin_instance_impl.cc b/content/renderer/pepper/pepper_plugin_instance_impl.cc
index 97a85c90f253966dd8e964bd7232cfe7d199e90f..d5cf0669292a139d37119e89cc0c678691723cf3 100644
--- a/content/renderer/pepper/pepper_plugin_instance_impl.cc
+++ b/content/renderer/pepper/pepper_plugin_instance_impl.cc
@@ -583,13 +583,9 @@ PepperPluginInstanceImpl::PepperPluginInstanceImpl(
       GetContentClient()->renderer()->IsExternalPepperPlugin(module->name()))
     external_document_load_ = true;
 
-  // TODO(tommycli): Insert heuristics to determine whether plugin content
-  // is peripheral here.
-  bool is_peripheral_content = true;
-  power_saver_enabled_ = is_peripheral_content &&
-      module->name() == kFlashPluginName &&
-      CommandLine::ForCurrentProcess()->HasSwitch(
-          switches::kEnablePluginPowerSaver);
+  power_saver_enabled_ = CommandLine::ForCurrentProcess()->HasSwitch(
+                             switches::kEnablePluginPowerSaver) &&
+                         IsPeripheralContent();
 
   if (power_saver_enabled_) {
     throttler_.reset(new PepperPluginInstanceThrottler(
@@ -3299,6 +3295,19 @@ void PepperPluginInstanceImpl::DidDataFromWebURLResponse(
   }
 }
 
+bool PepperPluginInstanceImpl::IsPeripheralContent() const {
+  if (module_->name() != kFlashPluginName)
+    return false;
+
+  // Peripheral plugin content is defined to be peripheral when the plugin
+  // content's origin differs from the top level frame's origin. For example:

[groby-ooo-7-16, 2014/10/23 20:00:45]

Technically, there are more reasons to consider content peripheral. Would you
mind changing the comment to "Content is considered to be cross-origin...."?

Followed by "currently, all cross-origin content is considered peripheral" or
something?

+  //  - Peripheral:      a.com -> b.com/plugin.swf
+  //  - Peripheral:      a.com -> b.com/iframe.html -> b.com/plugin.swf
+  //  - NOT peripheral:  a.com -> b.com/iframe-to-a.html -> a.com/plugin.swf
+  GURL top_frame_url = render_frame_->GetWebFrame()->top()->document().url();

[Charlie Reis, 2014/10/23 19:51:08]

Maybe we can throw a temporary check in until Alex fixes 426512, which returns
early if the main frame is remote.  (This will only affect --site-per-process
mode, breaking case 3 but avoiding a crash.)  Something like:

// TODO(alexmos): Update this to use the origin of the RemoteFrame when 426512
is fixed.
// For now, case 3 in the comment above doesn't work in --site-per-process mode.
if (render_frame_->GetWebFrame()->top()->isWebRemoteFrame())
  return true;

[groby-ooo-7-16, 2014/10/23 20:00:45]

+1 on this. I'd be surprised if there's a large number of sites that hosts the
content on the same domain but iframes through a different one, anyways.

[tommycli, 2014/10/23 20:51:28]

Done.

[tommycli, 2014/10/23 20:51:28]

Done.

+  return plugin_url_.GetOrigin() != top_frame_url.GetOrigin();
+}
+
 void PepperPluginInstanceImpl::SetPluginThrottled(bool throttled) {
   // Do not throttle if we've already disabled power saver.
   if (!power_saver_enabled_ && throttled)