Fix window zoom in a sane way, remove nasty casts.

content/public/browser/web_contents.h

Index: content/public/browser/web_contents.h
diff --git a/content/public/browser/web_contents.h b/content/public/browser/web_contents.h
index bcfe84fbbb04b454b36c63a56eef81ff4a6872a6..54bfdcc157322fd963b100e7fabfdd7bcbba850c 100644
--- a/content/public/browser/web_contents.h
+++ b/content/public/browser/web_contents.h
@@ -33,6 +33,7 @@ class TimeTicks;
 
 namespace gfx {
 class Rect;
+class Size;
 }
 
 namespace net {
@@ -328,6 +329,9 @@ class WebContents : public PageNavigator {
   virtual int GetMinimumZoomPercent() const = 0;
   virtual int GetMaximumZoomPercent() const = 0;
 
+  // Gets the preferred size of the contents.
+  virtual gfx::Size GetPreferredSize() const = 0;
+
   // Get the content restrictions (see content::ContentRestriction).
   virtual int GetContentRestrictions() const = 0;