Cleanup shared memory handling in DesktopCapturer interface.

webrtc/modules/desktop_capture/desktop_capturer.h

Index: webrtc/modules/desktop_capture/desktop_capturer.h
diff --git a/webrtc/modules/desktop_capture/desktop_capturer.h b/webrtc/modules/desktop_capture/desktop_capturer.h
index 7ad16364977416af3e1a79dc592cc0b9a0dd4a41..47f78dc3ff411510aabc417045419e010605487b 100644
--- a/webrtc/modules/desktop_capture/desktop_capturer.h
+++ b/webrtc/modules/desktop_capture/desktop_capturer.h
@@ -13,13 +13,14 @@
 
 #include <stddef.h>
 
+#include "webrtc/base/scoped_ptr.h"
 #include "webrtc/modules/desktop_capture/desktop_capture_types.h"
+#include "webrtc/modules/desktop_capture/shared_memory.h"
 
 namespace webrtc {
 
 class DesktopFrame;
 class DesktopRegion;
-class SharedMemory;
 
 // Abstract interface for screen and window capturers.
 class DesktopCapturer {
@@ -27,10 +28,10 @@ class DesktopCapturer {
   // Interface that must be implemented by the DesktopCapturer consumers.
   class Callback {
    public:
-    // Creates a new shared memory buffer for a frame create by the capturer.
-    // Should return null shared memory is not used for captured frames (in that
-    // case the capturer will allocate memory on the heap).
-    virtual SharedMemory* CreateSharedMemory(size_t size) = 0;
+    // Deprecated.
+    // TODO(sergeyu): Remove this method once all references to it are removed
+    // from chromium.
+    virtual SharedMemory* CreateSharedMemory(size_t size) { return nullptr; }
 
     // Called after a frame has been captured. Handler must take ownership of
     // |frame|. If capture has failed for any reason |frame| is set to NULL
@@ -47,6 +48,13 @@ class DesktopCapturer {
   // valid until capturer is destroyed.
   virtual void Start(Callback* callback) = 0;
 
+  // Sets SharedMemoryFactory that will be used to create buffers for the
+  // captured frames. The factory can be invoked on a thread other than the one
+  // where Capture() is called. It will be destroyed on the same thread. Shared
+  // memory is currently supported only by some DesktopCapturer implementations.
+  virtual void SetSharedMemoryFactory(
+      rtc::scoped_ptr<SharedMemoryFactory> shared_memory_factory) {}
+
   // Captures next frame. |region| specifies region of the capture target that
   // should be fresh in the resulting frame. The frame may also include fresh
   // data for areas outside |region|. In that case capturer will include these