Make it possible to set the display mode from the WebView API

public/web/WebView.h

Index: public/web/WebView.h
diff --git a/public/web/WebView.h b/public/web/WebView.h
index 0e9785c470db4882a6a6f7733218d0e47447292c..1273aaa5857fe658974cfa354749e62f27c9ce53 100644
--- a/public/web/WebView.h
+++ b/public/web/WebView.h
@@ -32,6 +32,7 @@
 #define WebView_h
 
 #include "../platform/WebColor.h"
+#include "../platform/WebDisplayMode.h"
 #include "../platform/WebPageVisibilityState.h"
 #include "../platform/WebString.h"
 #include "../platform/WebVector.h"
@@ -275,6 +276,9 @@ public:
     // The returned size has the page zoom factor applied.
     virtual WebSize contentsPreferredMinimumSize() = 0;
 
+    // Sets the display mode of the web app.
+    virtual void setDisplayMode(WebDisplayMode) = 0;
+
     // The ratio of the current device's screen DPI to the target device's screen DPI.
     virtual float deviceScaleFactor() const = 0;