Alternate computation of axObjectCacheOwner to improve perf

third_party/WebKit/Source/core/dom/Document.cpp

Index: third_party/WebKit/Source/core/dom/Document.cpp
diff --git a/third_party/WebKit/Source/core/dom/Document.cpp b/third_party/WebKit/Source/core/dom/Document.cpp
index 8ce94026ce0a80a89b6a8d59d8084551a8d60b6f..273fd5cb58948db813b8ae0544fdf3445be2033f 100644
--- a/third_party/WebKit/Source/core/dom/Document.cpp
+++ b/third_party/WebKit/Source/core/dom/Document.cpp
@@ -2311,22 +2311,22 @@ Document& Document::axObjectCacheOwner() const
     // of the AXObjectCache (http://crbug.com/510410), but the proper fix
     // will be for each Document to  have its own AXObjectCache
     // (http://crbug.com/532249).
-
+    Document* top = const_cast<Document*>(this);
     LocalFrame* frame = this->frame();
     if (!frame)
-        return *const_cast<Document*>(this);
-
-    frame = frame->localFrameRoot();
-    if (!frame || !frame->document())
-        return *const_cast<Document*>(this);
-
-    Document* owner = frame->document();
-    if (frame->pagePopupOwner()) {
-        ASSERT(!owner->m_axObjectCache);
-        return frame->pagePopupOwner()->document().axObjectCacheOwner();
+        return *top;
+    while (frame && frame->owner() && frame->owner()->isLocal()) {

[dcheng, 2015/12/28 22:12:19]

Nit: add a comment so someone (e.g. me) doesn't see this and think "hmm, why
don't I just use localFrameRoot()...)

[dmazzoni, 2015/12/29 00:13:08]

Done.

+        HTMLFrameOwnerElement* owner = toHTMLFrameOwnerElement(frame->owner());
+        top = &owner->document();
+        frame = top->frame();
+    }
+    if (top->frame() && top->frame()->pagePopupOwner()) {
+        ASSERT(!top->m_axObjectCache);
+        return top->frame()->pagePopupOwner()->document().axObjectCacheOwner();
     }
 
-    return *owner;
+    ASSERT(top);
+    return *top;
 }
 
 void Document::clearAXObjectCache()