Warn developers about deprecated features only once per page-load.

Source/core/page/DeprecationAgent.cpp

Index: Source/core/page/DeprecationAgent.cpp
diff --git a/Source/core/page/UseCounter.cpp b/Source/core/page/DeprecationAgent.cpp
similarity index 53%
copy from Source/core/page/UseCounter.cpp
copy to Source/core/page/DeprecationAgent.cpp
index 35eb07474e73b3f1423f8c9d1d0aa63a1d90138c..30768186b2a378c8fc21ff1d5f2c0192f09abc64 100644
--- a/Source/core/page/UseCounter.cpp
+++ b/Source/core/page/DeprecationAgent.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2012 Google, Inc. All rights reserved.
+ * Copyright (C) 2013 Google, Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -24,49 +24,39 @@
  */
 
 #include "config.h"
-#include "UseCounter.h"
+#include "DeprecationAgent.h"
 
-#include "DOMWindow.h"
 #include "Document.h"
-#include "HistogramSupport.h"
 #include "Page.h"
+#include "PageConsole.h"
+#include <wtf/BitVector.h>
+#include <wtf/Noncopyable.h>
+#include <wtf/OwnPtr.h>
+#include <wtf/PassOwnPtr.h>
+#include <wtf/text/WTFString.h>
 
 namespace WebCore {
 
-UseCounter::UseCounter()
-{
-}
+namespace {
 
-UseCounter::~UseCounter()
-{
-    // We always log PageDestruction so that we have a scale for the rest of the features.
-    HistogramSupport::histogramEnumeration("WebCore.FeatureObserver", PageDestruction, NumberOfFeatures);
+// Ensure that this stays in sync with the Feature enum.
+static const char* const deprecationMessages[] = {
+    "The 'X-WebKit-CSP' headers are deprecated; please consider using the canonical 'Content-Security-Policy' header instead."
+};
+
+// COMPILE_ASSERT(WTF_ARRAY_LENGTH(deprecationMessages) == static_cast<int>(WebCore::DeprecationAgent::NumberOfFeatures), DeprecationMessages_matches_Feature_enum);

[pfeldman, 2013/04/19 13:04:22]

It should work, right?

 
-    updateMeasurements();
 }
 
-void UseCounter::updateMeasurements()
+DeprecationAgent::DeprecationAgent()
 {
-    HistogramSupport::histogramEnumeration("WebCore.FeatureObserver", PageVisits, NumberOfFeatures);
-
-    if (!m_countBits)
-        return;
-
-    for (unsigned i = 0; i < NumberOfFeatures; ++i) {
-        if (m_countBits->quickGet(i))
-            HistogramSupport::histogramEnumeration("WebCore.FeatureObserver", i, NumberOfFeatures);
-    }
-
-    // Clearing count bits is timing sensitive.
-    m_countBits->clearAll();
 }
 
-void UseCounter::didCommitLoad()
+DeprecationAgent::~DeprecationAgent()
 {
-    updateMeasurements();
 }
 
-void UseCounter::observe(Document* document, Feature feature)
+void DeprecationAgent::notify(Document* document, Feature feature)
 {
     if (!document)
         return;
@@ -75,13 +65,24 @@ void UseCounter::observe(Document* document, Feature feature)
     if (!page)
         return;
 
-    page->useCounter()->didObserve(feature);
+    page->deprecationAgent()->sendNotification(page->console(), feature);
 }
 
-void UseCounter::observe(DOMWindow* domWindow, Feature feature)
+void DeprecationAgent::sendNotification(PageConsole* console, Feature feature)
 {
-    ASSERT(domWindow);
-    observe(domWindow->document(), feature);
+    ASSERT(feature < NumberOfFeatures);
+    ASSERT(console);
+
+    if (!m_countBits) {
+        m_countBits = adoptPtr(new BitVector(NumberOfFeatures));
+        m_countBits->clearAll();
+    }
+
+    if (m_countBits->quickGet(feature))

[pfeldman, 2013/04/19 13:04:22]

Is this covered with the tests? I.e. are you generating a number of them and
check that notification only comes once?

+        return;
+
+    m_countBits->quickSet(feature);
+    console->addMessage(DeprecationMessageSource, WarningMessageLevel, ASCIILiteral(deprecationMessages[feature]));
 }
 
 } // namespace WebCore