content: Cleanup class/struct forward declarations

content/browser/renderer_host/render_widget_host_view_android.h

Index: content/browser/renderer_host/render_widget_host_view_android.h
diff --git a/content/browser/renderer_host/render_widget_host_view_android.h b/content/browser/renderer_host/render_widget_host_view_android.h
index 590874305ae74ae9cad296ca31238e3e584a8494..10f335fe030b39206231da383cf90b5ffeed12ea 100644
--- a/content/browser/renderer_host/render_widget_host_view_android.h
+++ b/content/browser/renderer_host/render_widget_host_view_android.h
@@ -38,11 +38,10 @@
 #include "ui/gfx/selection_bound.h"
 #include "ui/touch_selection/touch_selection_controller.h"
 
+class GURL;
+
 namespace cc {
-class CopyOutputResult;
 class Layer;
-class SurfaceFactory;
-class SurfaceIdAllocator;
 }
 
 namespace ui {
@@ -50,8 +49,6 @@ struct DidOverscrollParams;
 }
 
 namespace blink {
-class WebExternalTextureLayer;
-class WebTouchEvent;
 class WebMouseEvent;
 }
 
@@ -61,7 +58,6 @@ class DelegatedFrameHostAndroid;
 
 namespace content {
 class ContentViewCoreImpl;
-class ContentViewCoreObserver;
 class OverscrollControllerAndroid;
 class RenderWidgetHost;
 class RenderWidgetHostImpl;