Blink API to allow mailbox usage with texture layers for WebGL and Canvas2D.

Source/Platform/chromium/public/WebExternalTextureMailbox.h

Index: Source/Platform/chromium/public/WebExternalTextureMailbox.h
diff --git a/Source/WebKit/chromium/public/WebMediaSource.h b/Source/Platform/chromium/public/WebExternalTextureMailbox.h
similarity index 84%
copy from Source/WebKit/chromium/public/WebMediaSource.h
copy to Source/Platform/chromium/public/WebExternalTextureMailbox.h
index ae7864b3090d45d155dce3a55872d6f6a27830c4..785e9181ae0c05a2448245a4d39e45452a63bd24 100644
--- a/Source/WebKit/chromium/public/WebMediaSource.h
+++ b/Source/Platform/chromium/public/WebExternalTextureMailbox.h
@@ -28,22 +28,22 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#ifndef WebMediaSource_h
-#define WebMediaSource_h
-
-#include "../../../Platform/chromium/public/WebURL.h"
-#include "WebTimeRange.h"
+#ifndef WebExternalTextureMailbox_h
+#define WebExternalTextureMailbox_h
 
 namespace WebKit {
 
-class WebMediaSourceClient;
+struct WebExternalTextureMailbox {
+    signed char name[64];
+    unsigned syncPoint;
 
-class WebMediaSource {
-public:
-    virtual ~WebMediaSource() { };
-    virtual void open(WebMediaSourceClient*) = 0;
+    WebExternalTextureMailbox()
+        : syncPoint(0)
+    {
+        memset(name, 0, sizeof(name));
+    }
 };
 
 } // namespace WebKit
 
-#endif
+#endif // WebExternalTextureMailbox_h