Throttle rendering pipeline for invisible iframes

Source/core/layout/compositing/DeprecatedPaintLayerCompositor.cpp

Index: Source/core/layout/compositing/DeprecatedPaintLayerCompositor.cpp
diff --git a/Source/core/layout/compositing/DeprecatedPaintLayerCompositor.cpp b/Source/core/layout/compositing/DeprecatedPaintLayerCompositor.cpp
index 53657cedd899cc8ab4f52e093fa34c4a0a19b8e6..7cebb8ea09565d0d3c692fb33bc5dfe124428dbd 100644
--- a/Source/core/layout/compositing/DeprecatedPaintLayerCompositor.cpp
+++ b/Source/core/layout/compositing/DeprecatedPaintLayerCompositor.cpp
@@ -194,6 +194,10 @@ void updateDescendantDependentFlagsForEntireSubtree(DeprecatedPaintLayer& layer)
 
 void DeprecatedPaintLayerCompositor::updateIfNeededRecursive()
 {
+    FrameView* view = m_layoutView.frameView();
+    if (view->shouldThrottleStyleLayoutAndCompositingUpdates())
+        return;
+
     for (Frame* child = m_layoutView.frameView()->frame().tree().firstChild(); child; child = child->tree().nextSibling()) {
         if (!child->isLocalFrame())
             continue;
@@ -238,8 +242,14 @@ void DeprecatedPaintLayerCompositor::updateIfNeededRecursive()
     ASSERT(lifecycle().state() == DocumentLifecycle::CompositingClean);
     assertNoUnresolvedDirtyBits();
     for (Frame* child = m_layoutView.frameView()->frame().tree().firstChild(); child; child = child->tree().nextSibling()) {
-        if (child->isLocalFrame())
-            toLocalFrame(child)->contentLayoutObject()->compositor()->assertNoUnresolvedDirtyBits();
+        if (!child->isLocalFrame())
+            continue;
+        LocalFrame* localFrame = toLocalFrame(child);
+        if (FrameView* childView = localFrame->view()) {

[ojan, 2015/09/01 19:56:48]

Nit: Looks like you're going from Frame-->FrameView-->
shouldThrottleStyleLayoutAndCompositingUpdates in a number of places. Maybe add
a shouldThrottleStyleLayoutAndCompositingUpdates to Frame that just passes
through to FrameView (and does the null check of course)? That would make the
calling code a bit simpler.

[Sami, 2015/09/02 10:46:02]

Good idea, done. (I assume you meant LocalFrame instead of Frame).

+            if (childView->shouldThrottleStyleLayoutAndCompositingUpdates())
+                continue;
+        }
+        localFrame->contentLayoutObject()->compositor()->assertNoUnresolvedDirtyBits();
     }
 #endif
 }