Add missing #include "ui/gfx/transform.h" to sync_compositor_messages.h

Bug: 1019015

Change-Id: I8351899f0781392582aa0a2a3acfcbea1ebe70d6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1928306Reviewed-by: Oliver Chang <ochang@chromium.org>
Commit-Queue: Michael Spang <spang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#718079}

content/common/input/sync_compositor_messages.h

@@ -12,6 +12,7 @@
 #include "ipc/ipc_message_macros.h"
 #include "ui/gfx/geometry/point.h"
 #include "ui/gfx/geometry/scroll_offset.h"
+#include "ui/gfx/transform.h"
 
 #ifndef INTERNAL_CONTENT_COMMON_SYNC_COMPOSITOR_MESSAGES_H_
 #define INTERNAL_CONTENT_COMMON_SYNC_COMPOSITOR_MESSAGES_H_