Add UMA metrics for root scroller intervention to track forcing passive breakage.

third_party/WebKit/Source/core/testing/Internals.cpp

Index: third_party/WebKit/Source/core/testing/Internals.cpp
diff --git a/third_party/WebKit/Source/core/testing/Internals.cpp b/third_party/WebKit/Source/core/testing/Internals.cpp
index 33b5df0e89dd0152b0f46cfba0eb594ae0df6aa9..436435f3ad2a42af9ce65619aade882f65dc9408 100644
--- a/third_party/WebKit/Source/core/testing/Internals.cpp
+++ b/third_party/WebKit/Source/core/testing/Internals.cpp
@@ -138,6 +138,7 @@
 #include "platform/heap/Handle.h"
 #include "platform/inspector_protocol/FrontendChannel.h"
 #include "platform/scroll/ProgrammaticScrollAnimator.h"
+#include "platform/testing/HistogramTester.h"
 #include "platform/weborigin/SchemeRegistry.h"
 #include "public/platform/Platform.h"
 #include "public/platform/WebConnectionType.h"
@@ -221,6 +222,7 @@ Internals::~Internals()
 }
 
 static RuntimeEnabledFeatures::Backup* sFeaturesBackup = nullptr;
+static std::unique_ptr<HistogramTester> sHistogramSnapshot;
 
 void Internals::resetToConsistentState(Page* page)
 {
@@ -228,6 +230,8 @@ void Internals::resetToConsistentState(Page* page)
 
     if (!sFeaturesBackup)
         sFeaturesBackup = new RuntimeEnabledFeatures::Backup;
+    if (!sHistogramSnapshot)
+        sHistogramSnapshot.reset(new HistogramTester());
     sFeaturesBackup->restore();
     page->setIsCursorVisible(true);
     page->setPageScaleFactor(1);
@@ -386,6 +390,16 @@ void Internals::clearHitTestCache(Document* doc, ExceptionState& exceptionState)
     doc->layoutViewItem().clearHitTestCache();
 }
 
+int Internals::histogramCount(const String& name, int bucket) const
+{
+    return sHistogramSnapshot->histogramCount(name.utf8().data(), bucket);
+}
+
+void Internals::clearHistogramCounts()
+{
+    sHistogramSnapshot.reset(new HistogramTester());
+}
+
 bool Internals::isPreloaded(const String& url)
 {
     return isPreloadedBy(url, contextDocument());