Make PageScaleFactor work for oopif subframes.

third_party/WebKit/public/web/WebView.h

Index: third_party/WebKit/public/web/WebView.h
diff --git a/third_party/WebKit/public/web/WebView.h b/third_party/WebKit/public/web/WebView.h
index a08cf28f3ed97fc5f461bbc54593320de871c9d1..a49520905e869082d9d121201b7623fa9fdc0c3c 100644
--- a/third_party/WebKit/public/web/WebView.h
+++ b/third_party/WebKit/public/web/WebView.h
@@ -266,6 +266,9 @@ class WebView : protected WebWidget {
   // Scales the page without affecting layout by using the visual viewport.
   virtual void setPageScaleFactor(float) = 0;
 
+  // Returns the scale factor clamped within the current limits.
+  virtual float clampPageScaleFactorToLimits(float) const = 0;
+
   // Sets the offset of the visual viewport within the main frame, in
   // partial CSS pixels. The offset will be clamped so the visual viewport
   // stays within the frame's bounds.