Plugin Power Saver: Throttle 'large' plugins that appear small.

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 c7e400527979f8b71886e9e2339c27c426cf720a..0b86054c066f3036808685e2ecaaa081ba128430 100644
--- a/content/renderer/pepper/pepper_plugin_instance_impl.cc
+++ b/content/renderer/pepper/pepper_plugin_instance_impl.cc
@@ -809,19 +809,9 @@ bool PepperPluginInstanceImpl::Initialize(
   if (!render_frame_)
     return false;
 
-  if (is_flash_plugin_ && RenderThread::Get()) {
-    RenderThread::Get()->RecordAction(
-        base::UserMetricsAction("Flash.PluginInstanceCreated"));
-    blink::WebRect bounds = container()->element().boundsInViewportSpace();
-    RecordFlashSizeMetric(bounds.width, bounds.height);
-  }
-
   if (throttler) {
     throttler_ = throttler.Pass();
     throttler_->AddObserver(this);
-    throttler_->Initialize(render_frame_, plugin_url_.GetOrigin(),
-                           module()->name(),
-                           container()->element().boundsInViewportSpace());
   }
 
   message_channel_ = MessageChannel::Create(this, &message_channel_object_);
@@ -1233,8 +1223,9 @@ PP_Var PepperPluginInstanceImpl::GetInstanceObject(v8::Isolate* isolate) {
 }
 
 void PepperPluginInstanceImpl::ViewChanged(
-    const gfx::Rect& position,
+    const gfx::Rect& window,
     const gfx::Rect& clip,
+    const gfx::Rect& unobscured,
     const std::vector<gfx::Rect>& cut_outs_rects) {
   // WebKit can give weird (x,y) positions for empty clip rects (since the
   // position technically doesn't matter). But we want to make these
@@ -1244,9 +1235,11 @@ void PepperPluginInstanceImpl::ViewChanged(
   if (!clip.IsEmpty())
     new_clip = clip;
 
+  unobscured_ = unobscured;
+
   cut_outs_rects_ = cut_outs_rects;
 
-  view_data_.rect = PP_FromGfxRect(position);
+  view_data_.rect = PP_FromGfxRect(window);
   view_data_.clip_rect = PP_FromGfxRect(clip);
   view_data_.device_scale = container_->deviceScaleFactor();
   view_data_.css_scale =
@@ -1288,7 +1281,12 @@ void PepperPluginInstanceImpl::ViewChanged(
 
   UpdateFlashFullscreenState(fullscreen_container_ != NULL);
 
-  SendDidChangeView();
+  // During plugin initialization, there are often re-layouts. Avoid sending
+  // intermediate sizes the plugin and throttler.
+  if (sent_initial_did_change_view_)
+    SendDidChangeView();
+  else
+    ScheduleAsyncDidChangeView();
 }
 
 void PepperPluginInstanceImpl::SetWebKitFocus(bool has_focus) {
@@ -1630,6 +1628,20 @@ void PepperPluginInstanceImpl::SendDidChangeView() {
 
   ppapi::ViewData view_data = view_data_;
 
+  if (!sent_initial_did_change_view_) {

[piman, 2015/04/01 01:02:41]

So, you may be getting into this code more than once. SendDidChangeView is
called from various places, but we will just early out if there is a pending
posted task, on l.1655, in which case sent_initial_did_change_view_ will not be
set to true.

The following order is possible:

- Initialization (sent_initial_did_change_view_ is false)
- ScheduleAsyncDidChangeView (sent_initial_did_change_view_ is still false)
- something calls SendDidChangeView directly (e.g. ResetAsProxied or
PageVisibilityChanged), and we get here (sent_initial_did_change_view_ is still
false) but we early exit on l.1655 because a task is pending, so
sent_initial_did_change_view_ is not set to true
- the task executes, and we get here again, sent_initial_did_change_view_ is
still false


Maybe both this code and the code below (the if (throttler_ &&
throttler_->IsThrottled()) block) should move after l.1655, right before
sent_initial_did_change_view_ is set to true (that way you're guaranteed it's
done exactly once).

[tommycli, 2015/04/01 18:55:28]

Done. Thanks for the explanation. That's a pretty tricky setup.

I was unable to move that block under 1655 as that conditional uses the
throttler-modified view data. However, I was able to move the async view change
early exit to the very top.

+    if (is_flash_plugin_ && RenderThread::Get()) {
+      RenderThread::Get()->RecordAction(
+          base::UserMetricsAction("Flash.PluginInstanceCreated"));
+      RecordFlashSizeMetric(unobscured_.width(), unobscured_.height());
+    }
+
+    // Initialize the throttler if necessary.
+    if (throttler_) {
+      throttler_->Initialize(render_frame_, plugin_url_.GetOrigin(),
+                             module()->name(), unobscured_.size());
+    }
+  }
+
   // When plugin content is throttled, fake the page being offscreen. We cannot
   // send empty view data here, as some plugins rely on accurate view data.
   if (throttler_ && throttler_->IsThrottled()) {