Introduce vaLockBuffer APIs in libva.

Reason that add this change:
1080p video playback on Tizen is quite unsmooth on VTC-1010, with only 15 render
fps and ~70% CPU usage. Ozone-wl landed a workaround solution that enables a
zero buffer copy method that uses libva vaLockBuffer APIs which gains much better
performance than previous method.
intel/ozone-wayland#260

In order to make the change also benifit Crosswalk/Tizen, we should add the
vaLockBuffer API declarations inside Chromium Crosswalk to compile
the code successfully.

The long term goal of our work would be landing those API declarations inside
Chromium upstream, after the API implementations are landed in libva and
libva-driver upstream.

Therefore, this CL is a temporary solution. It would be reverted after the long
term goal is achived.

third_party/libva/va/va.h

@@ -78,6 +78,7 @@
 #ifndef _VA_H_
 #define _VA_H_
 
+#include <stddef.h>
 #include <stdint.h>
 #include <va/va_version.h>
 
@@ -1851,6 +1852,116 @@ VAStatus vaDestroyBuffer (
     VABufferID buffer_id
 );
 
+/** VA buffer information */
+typedef struct {
+    /** Buffer handle */
+    uintptr_t           handle;
+    /** Buffer type (See VABufferType). */
+    uint32_t            type;
+    /**
+     * Buffer memory type (See VASurfaceAttribMemoryType).
+     *
+     * On input to vaLockBuffer(), this field can serve as a hint to
+     * specify the set of memory types the caller is interested in. On
+     * successful return from vaLockBuffer(), the field is updated
+     * with the best matching memory type.
+     */
+    uint32_t            mem_type;
+    /** Size of the underlying buffer. */
+    size_t              mem_size;
+} VABufferInfo;
+
+/**
+ * Locks buffer for external API usage.
+ *
+ * Locks the VA buffer object buf_id for external API usage like
+ * EGL or OpenCL (OCL). This function is a synchronization point. This
+ * means that any pending operation is guaranteed to be completed
+ * prior to returning from the function.
+ *
+ * If the referenced VA buffer object is the backing store of a VA
+ * surface, then this function acts as if vaSyncSurface() on the
+ * parent surface was called first.
+ *
+ * The VABufferInfo argument shall be zero'ed on input. On
+ * successful output, the data structure is filled in with all the
+ * necessary buffer level implementation details like handle, type,
+ * memory type and memory size.
+ *
+ * Note: the external API implementation, or the application, can
+ * express the memory types it is interested in by filling in the
+ * mem_type field accordingly. On successful output, the memory type
+ * that fits best the request and that was used is updated in the
+ * VABufferInfo data structure. If none of the supplied memory types
+ * is supported, then a VA_STATUS_ERROR_UNSUPPORTED_MEMORY_TYPE
+ * error is returned.
+ *
+ * The VABufferInfo data is valid until vaUnlockBuffer() is
+ * called. Besides, no additional operation is allowed on any of the
+ * buffer parent object until vaUnlockBuffer() is called. e.g. decoding
+ * into a VA surface backed with the supplied VA buffer object
+ * buf_id would fail with a VA_STATUS_ERROR_SURFACE_BUSY error.
+ *
+ * Possible errors:
+ * - VA_STATUS_ERROR_UNIMPLEMENTED: the VA driver implementation
+ *   does not support this interface
+ * - VA_STATUS_ERROR_INVALID_DISPLAY: an invalid display was supplied
+ * - VA_STATUS_ERROR_INVALID_BUFFER: an invalid buffer was supplied
+ * - VA_STATUS_ERROR_UNSUPPORTED_BUFFERTYPE: the implementation
+ *   does not support exporting buffers of the specified type
+ * - VA_STATUS_ERROR_UNSUPPORTED_MEMORY_TYPE: none of the requested
+ *   memory types in \ref VABufferInfo.mem_type was supported
+ *
+ * @param[in] dpy               the VA display
+ * @param[in] buf_id            the VA buffer
+ * @param[in,out] buf_info_ptr  the VA buffer information
+ * @return VA_STATUS_SUCCESS if successful
+ */
+VAStatus
+vaLockBuffer(
+    VADisplay           dpy,
+    VABufferID          buf_id,
+    VABufferInfo *      buf_info_ptr
+);
+
+/**
+ * Unlocks buffer after usage from external API.
+ *
+ * Unlocks the VA buffer object buf_id from external API usage like
+ * EGL or OpenCL (OCL). This function is a synchronization point. This
+ * means that any pending operation is guaranteed to be completed
+ * prior to returning from the function.
+ *
+ * The VABufferInfo argument shall point to the original data
+ * structure that was obtained from vaLockBuffer(), unaltered. This is
+ * necessary so that the VA driver implementation could deallocate any
+ * resources that were needed.
+ *
+ * In any case, returning from this function invalidates any contents
+ * in VABufferInfo. i.e. the underlyng buffer handle is no longer
+ * valid. Therefore, VA driver implementations are free to reset this
+ * data structure to safe defaults.
+ *
+ * Possible errors:
+ * - VA_STATUS_ERROR_UNIMPLEMENTED: the VA driver implementation
+ *   does not support this interface
+ * - VA_STATUS_ERROR_INVALID_DISPLAY: an invalid display was supplied
+ * - VA_STATUS_ERROR_INVALID_BUFFER: an invalid buffer was supplied
+ * - VA_STATUS_ERROR_UNSUPPORTED_BUFFERTYPE: the implementation
+ *   does not support exporting buffers of the specified type
+ *
+ * @param[in] dpy               the VA display
+ * @param[in] buf_id            the VA buffer
+ * @param[in,out] buf_info_ptr  the VA buffer information
+ * @return VA_STATUS_SUCCESS if successful
+ */
+VAStatus
+vaUnlockBuffer(
+    VADisplay           dpy,
+    VABufferID          buf_id,
+    VABufferInfo *      buf_info_ptr
+);
+
 /*
 Render (Decode) Pictures
 

third_party/libva/va/va_backend.h

@@ -420,6 +420,20 @@ struct VADriverVTable
             VASurfaceAttrib    *attrib_list,
             unsigned int       *num_attribs
         );
+
+        VAStatus
+        (*vaLockBuffer)(
+            VADriverContextP    ctx,
+            VABufferID          buf_id,
+            VABufferInfo *      buf_info_ptr
+        );
+
+        VAStatus
+        (*vaUnlockBuffer)(
+            VADriverContextP    ctx,
+            VABufferID          buf_id,
+            VABufferInfo *      buf_info_ptr
+        );
 };
 
 struct VADriverContext