Plumb event flags (shift/alt/ctrl modifiers) for drag/drop events to WebKit.

content/common/drag_messages.h

Index: content/common/drag_messages.h
diff --git a/content/common/drag_messages.h b/content/common/drag_messages.h
index 730782bd18571d839691adb1f79ffd3a77e6863c..29aaea8230cbd28011ea7d43d591173e39dbf56e 100644
--- a/content/common/drag_messages.h
+++ b/content/common/drag_messages.h
@@ -37,22 +37,25 @@ IPC_STRUCT_TRAITS_END()
 
 // Messages sent from the browser to the renderer.
 
-IPC_MESSAGE_ROUTED4(DragMsg_TargetDragEnter,
+IPC_MESSAGE_ROUTED5(DragMsg_TargetDragEnter,
                     WebDropData /* drop_data */,
                     gfx::Point /* client_pt */,
                     gfx::Point /* screen_pt */,
-                    WebKit::WebDragOperationsMask /* ops_allowed */)
+                    WebKit::WebDragOperationsMask /* ops_allowed */,
+                    int /* key_modifiers */)
 
-IPC_MESSAGE_ROUTED3(DragMsg_TargetDragOver,
+IPC_MESSAGE_ROUTED4(DragMsg_TargetDragOver,
                     gfx::Point /* client_pt */,
                     gfx::Point /* screen_pt */,
-                    WebKit::WebDragOperationsMask /* ops_allowed */)
+                    WebKit::WebDragOperationsMask /* ops_allowed */,
+                    int /* key_modifiers */)
 
 IPC_MESSAGE_ROUTED0(DragMsg_TargetDragLeave)
 
-IPC_MESSAGE_ROUTED2(DragMsg_TargetDrop,
+IPC_MESSAGE_ROUTED3(DragMsg_TargetDrop,
                     gfx::Point /* client_pt */,
-                    gfx::Point /* screen_pt */)
+                    gfx::Point /* screen_pt */,
+                    int /* key_modifiers */)
 
 // Notifies the renderer of updates in mouse position of an in-progress
 // drag.  if |ended| is true, then the user has ended the drag operation.