Log to UMA when x-origin frames (1) are created and (2) become visible

third_party/WebKit/Source/core/frame/LocalFrame.cpp

Index: third_party/WebKit/Source/core/frame/LocalFrame.cpp
diff --git a/third_party/WebKit/Source/core/frame/LocalFrame.cpp b/third_party/WebKit/Source/core/frame/LocalFrame.cpp
index 57c4765081cc252bb1073a41379e3bf0d86f6413..86bb0881353d9c7fdbc5a8da10c32415cc03b565 100644
--- a/third_party/WebKit/Source/core/frame/LocalFrame.cpp
+++ b/third_party/WebKit/Source/core/frame/LocalFrame.cpp
@@ -69,6 +69,7 @@
 #include "core/paint/TransformRecorder.h"
 #include "core/svg/SVGDocumentExtensions.h"
 #include "platform/DragImage.h"
+#include "platform/Histogram.h"
 #include "platform/JSONValues.h"
 #include "platform/PluginScriptForbiddenScope.h"
 #include "platform/RuntimeEnabledFeatures.h"
@@ -217,6 +218,21 @@ inline float parentTextZoomFactor(LocalFrame* frame)
     return toLocalFrame(parent)->textZoomFactor();
 }
 
+// These are logged to UMA, so don't re-arrange them without creating a new histogram.
+enum FrameStateForDeferredLoading {
+    Created,
+    WouldLoadBecauseVisible,
+    // TODO(dgrogan): Add WouldLoadBecauseTopOrLeft, WouldLoadBecauseDisplayNone, etc
+
+    FrameStateForDeferredLoadingEnd
+};
+
+void RecordStateToHistogram(FrameStateForDeferredLoading state)
+{
+    DEFINE_STATIC_LOCAL(EnumerationHistogram, unseenFrameHistogram, ("DeferredFrameLoading.StatesV1", FrameStateForDeferredLoadingEnd));
+    unseenFrameHistogram.count(state);
+}
+
 } // namespace
 
 template class CORE_TEMPLATE_EXPORT Supplement<LocalFrame>;
@@ -806,6 +822,8 @@ inline LocalFrame::LocalFrame(FrameLoaderClient* client, FrameHost* host, FrameO
     , m_textZoomFactor(parentTextZoomFactor(this))
     , m_inViewSourceMode(false)
     , m_interfaceProvider(interfaceProvider)
+    , m_visibilityWasLogged(false)
+    , m_creationWasLogged(false)
 {
     if (isLocalRoot())
         m_instrumentingAgents = new InstrumentingAgents();
@@ -837,6 +855,22 @@ PluginData* LocalFrame::pluginData() const
     return page()->pluginData();
 }
 
+void LocalFrame::didInstallNewRealDocument()
+{
+    if (!m_creationWasLogged && isCrossOriginSubframe()) {
+        m_creationWasLogged = true;
+        RecordStateToHistogram(Created);
+    }
+}
+
+void LocalFrame::onVisibilityMaybeChanged(bool visible)
+{
+    if (visible && !m_visibilityWasLogged && isCrossOriginSubframe()) {
+        m_visibilityWasLogged = true;
+        RecordStateToHistogram(WouldLoadBecauseVisible);
+    }
+}
+
 DEFINE_WEAK_IDENTIFIER_MAP(LocalFrame);
 
 FrameNavigationDisabler::FrameNavigationDisabler(LocalFrame& frame)