content: Cleanup class/struct forward declarations

content/renderer/renderer_blink_platform_impl.h

Index: content/renderer/renderer_blink_platform_impl.h
diff --git a/content/renderer/renderer_blink_platform_impl.h b/content/renderer/renderer_blink_platform_impl.h
index f07ede475f26fbca6e6ce1be36891f8a6a1c416c..3d1dfe33fbcdb9f1b1c97a59126c580a538fe896 100644
--- a/content/renderer/renderer_blink_platform_impl.h
+++ b/content/renderer/renderer_blink_platform_impl.h
@@ -25,10 +25,6 @@
 #include "third_party/WebKit/public/platform/modules/indexeddb/WebIDBFactory.h"
 #include "third_party/WebKit/public/platform/modules/screen_orientation/WebScreenOrientationType.h"
 
-namespace cc {
-class ContextProvider;
-}
-
 namespace IPC {
 class SyncMessageFilter;
 }
@@ -36,7 +32,6 @@ class SyncMessageFilter;
 namespace blink {
 namespace scheduler {
 class RendererScheduler;
-class WebThreadImplForRendererScheduler;
 }
 class WebCanvasCaptureHandler;
 class WebDeviceMotionData;
@@ -59,11 +54,9 @@ class LocalStorageCachedAreas;
 class PlatformEventObserverBase;
 class QuotaMessageFilter;
 class RendererClipboardDelegate;
-class RenderView;
 class ThreadSafeSender;
 class WebClipboardImpl;
 class WebDatabaseObserverImpl;
-class WebFileSystemImpl;
 
 class CONTENT_EXPORT RendererBlinkPlatformImpl : public BlinkPlatformImpl {
  public: