cc: Various code safety improvements in video compositing code.

cc/layers/video_frame_provider.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CC_LAYERS_VIDEO_FRAME_PROVIDER_H_
 #define CC_LAYERS_VIDEO_FRAME_PROVIDER_H_
 
 #include "base/memory/ref_counted.h"
+#include "cc/base/cc_export.h"
 
 namespace media {
 class VideoFrame;
 }
 
 namespace cc {
 
 // Threading notes: This class may be used in a multi threaded manner.
 // Specifically, the implementation may call GetCurrentFrame() or
 // PutCurrentFrame() from the compositor thread. If so, the caller is
 // responsible for making sure Client::DidReceiveFrame() and
 // Client::DidUpdateMatrix() are only called from this same thread.
-class VideoFrameProvider {
+class CC_EXPORT VideoFrameProvider {

[danakj, 2015/03/26 22:38:35]

we don't need to export pure virtual things right?

[sunnyps, 2015/03/27 00:38:46]

I think we do in this case - my CL fails on dll builds. I think it worked before
because we only used an inline function (active_video_layer) of
VideoFrameProviderClientImpl which is a subclass of VideoFrameProvider::Client.
As soon as I changed that to normal function call I got build errors. In the
test which uses active_video_layer there's a static cast from
VideoFrameProvider::Client (which was not exported) to
VideoFrameProviderClientImpl (which was/is exported). Could be that or the 1
million other special cases in C++. :)

  public:
   virtual ~VideoFrameProvider() {}
 
-  class Client {
+  class CC_EXPORT Client {
    public:
     // Provider will call this method to tell the client to stop using it.
     // StopUsingProvider() may be called from any thread. The client should
     // block until it has PutCurrentFrame() any outstanding frames.
     virtual void StopUsingProvider() = 0;
 
     // Notifies the provider's client that a call to GetCurrentFrame() will
     // return new data.
     virtual void DidReceiveFrame() = 0;
 
@@ skipping 18 matching lines @@
   // called after GetCurrentFrame(). Frames passed into this method
   // should no longer be referenced after the call is made. Only the current
   // provider client should call this function.
   virtual void PutCurrentFrame(
       const scoped_refptr<media::VideoFrame>& frame) = 0;
 };
 
 }  // namespace cc
 
 #endif  // CC_LAYERS_VIDEO_FRAME_PROVIDER_H_