Clean up .gypi and no-op GetCompositingSurface on TOUCH_UI.

chrome/browser/renderer_host/render_widget_host_view_views_touch.cc

Index: chrome/browser/renderer_host/render_widget_host_view_views_touch.cc
diff --git a/chrome/browser/renderer_host/render_widget_host_view_views_touch.cc b/chrome/browser/renderer_host/render_widget_host_view_views_touch.cc
index 09b0726283154499c707bd01b85ee01c00401474..94f382fb1f47aea73a0ff2244ac1ef13c07169ef 100644
--- a/chrome/browser/renderer_host/render_widget_host_view_views_touch.cc
+++ b/chrome/browser/renderer_host/render_widget_host_view_views_touch.cc
@@ -190,6 +190,13 @@ RenderWidgetHostView*
   return reinterpret_cast<RenderWidgetHostView*>(user_data);
 }
 
+gfx::PluginWindowHandle RenderWidgetHostViewViews::GetCompositingSurface() {
+  // On TOUCH_UI builds, the GPU process renders to an offscreen surface
+  // (created by the GPU process), which is later displayed by the browser.
+  // As the GPU process creates this surface, we can return any non-zero value.
+  return 1;
+}
+
 void RenderWidgetHostViewViews::AcceleratedSurfaceSetIOSurface(
     int32 width, int32 height, uint64 surface_id) {
   accelerated_surface_containers_[surface_id] =