Deferred frame loading stats v2

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

Index: third_party/WebKit/Source/core/dom/Document.h
diff --git a/third_party/WebKit/Source/core/dom/Document.h b/third_party/WebKit/Source/core/dom/Document.h
index dbf24300948695646d45183b83c1007d842adeab..3a2c42933206dc26417b50950cade4be169c7328 100644
--- a/third_party/WebKit/Source/core/dom/Document.h
+++ b/third_party/WebKit/Source/core/dom/Document.h
@@ -235,6 +235,28 @@ enum CreateElementFlags {
   CreatedByFragmentParser = CreatedByParser | AsynchronousCustomElements,
 };
 
+// Collect data about deferred loading of offscreen cross-origin documents. All
+// cross-origin documents log Created. Only those that would load log a reason.
+// We can then see the % of cross-origin documents that never have to load.
+// See https://crbug.com/635105.
+// Logged to UMA, don't re-arrange entries without creating a new histogram.
+enum WouldLoadReason {
+  Created,
+  // If outer and inner frames aren't in the same process we can't determine
+  // if the inner frame is visible, so just load it.

[dcheng, 2016/10/13 23:00:43]

Maybe add a TODO pointing to https://crbug.com/650433 here: we do plan on fixing
this eventually.

[dgrogan, 2016/10/14 21:45:08]

Done.

+  WouldLoadOutOfProcess,
+  // The next four indicate frames that are probably used for cross-origin
+  // communication.
+  WouldLoadDisplayNone,
+  WouldLoadZeroByZero,
+  WouldLoadAbove,
+  WouldLoadLeft,
+  // We have to load documents in visible frames.
+  WouldLoadVisible,
+
+  WouldLoadReasonEnd
+};
+
 using DocumentClassFlags = unsigned char;
 
 class CORE_EXPORT Document : public ContainerNode,
@@ -1280,7 +1302,8 @@ class CORE_EXPORT Document : public ContainerNode,
 
   bool isInMainFrame() const;
 
-  void onVisibilityMaybeChanged(bool visible);
+  void wouldLoadBecause(WouldLoadReason);
+  WouldLoadReason wouldLoadReason() { return m_wouldLoadReason; }
 
   PropertyRegistry* propertyRegistry();
 
@@ -1636,7 +1659,7 @@ class CORE_EXPORT Document : public ContainerNode,
 
   Member<SnapCoordinator> m_snapCoordinator;
 
-  bool m_visibilityWasLogged;
+  WouldLoadReason m_wouldLoadReason;
 
   Member<PropertyRegistry> m_propertyRegistry;
 };