Add support for runtime fall-back from o3d to o2d.

core/cross/client_info.h

Index: core/cross/client_info.h
===================================================================
--- core/cross/client_info.h	(revision 75614)
+++ core/cross/client_info.h	(working copy)
@@ -77,16 +77,7 @@
 
   // Whether render in 2d Mode
   bool render_2d() const {
-#if defined(SUPPORT_CAIRO) && defined(FORCE_CAIRO)
-    // Force Cairo o2d mode for testing purposes
-    return true;
-#elif defined(SUPPORT_CAIRO)
-    // Some day when we have fallback from o3d to o2d,
-    // this will have to support logic returning actual o2d vs. o3d mode.
-    return false;
-#else
-    return false;
-#endif
+    return render_2d_;
   }
 
   // Whether or not the underlying GPU supports non power of 2 textures.
@@ -113,6 +104,7 @@
   int buffer_memory_used_;
   bool software_renderer_;
   bool non_power_of_two_textures_;
+  bool render_2d_;
   String version_;
 };
 
@@ -145,6 +137,10 @@
     client_info_.non_power_of_two_textures_ = npot;
   }
 
+  void SetRender2d(bool render2d) {
+    client_info_.render_2d_ = render2d;
+  }
+
 private:
   ServiceImplementation<ClientInfoManager> service_;