Add fixed raster scale use counter histograms.

third_party/WebKit/Source/web/WebViewImpl.cpp

Index: third_party/WebKit/Source/web/WebViewImpl.cpp
diff --git a/third_party/WebKit/Source/web/WebViewImpl.cpp b/third_party/WebKit/Source/web/WebViewImpl.cpp
index dbce5b06b65f7e4ff4ef9e4783670e765bcfada8..05e6731f78389facf439f5f7deda124fa8097638 100644
--- a/third_party/WebKit/Source/web/WebViewImpl.cpp
+++ b/third_party/WebKit/Source/web/WebViewImpl.cpp
@@ -59,6 +59,7 @@
 #include "core/frame/Settings.h"
 #include "core/frame/SmartClip.h"
 #include "core/frame/TopControls.h"
+#include "core/frame/UseCounter.h"
 #include "core/frame/VisualViewport.h"
 #include "core/html/HTMLInputElement.h"
 #include "core/html/HTMLMediaElement.h"
@@ -2802,6 +2803,17 @@ void WebViewImpl::didChangeWindowResizerRect()
         mainFrameImpl()->frameView()->windowResizerRectChanged();
 }
 
+void WebViewImpl::reportFixedRasterScaleUseCounters(bool hasBlurryContent, bool hasPotentialPerformanceRegression)
+{
+    if (!mainFrameImpl() || !mainFrameImpl()->frame()->isLocalFrame())
+        return;
+    Document* document = mainFrameImpl()->frame()->document();
+    if (hasBlurryContent)
+        UseCounter::count(document, UseCounter::FixedRasterScaleBlurryContent);
+    if (hasPotentialPerformanceRegression)
+        UseCounter::count(document, UseCounter::FixedRasterScalePotentialPerformanceRegression);

[esprehn, 2016/05/16 04:59:24]

Why can't we just handle this inside blink? Having the embedder call into blink
for a UseCounter is not really what we want with Onion Soup. 

+}
+
 // WebView --------------------------------------------------------------------
 
 WebSettingsImpl* WebViewImpl::settingsImpl()