Add basic support to dump pixel results

content/shell/shell_messages.h

Index: content/shell/shell_messages.h
diff --git a/content/shell/shell_messages.h b/content/shell/shell_messages.h
index 50ce12249860960dc8983b47427ac98733ee01a2..3b483aebe33a3aee654248fb9a9c1eb76e06d51d 100644
--- a/content/shell/shell_messages.h
+++ b/content/shell/shell_messages.h
@@ -5,7 +5,9 @@
 // Multiply-included file, no traditional include guard.
 #include <string>
 
+#include "content/public/common/common_param_traits.h"
 #include "ipc/ipc_message_macros.h"
+#include "third_party/skia/include/core/SkBitmap.h"
 
 #define IPC_MESSAGE_START ShellMsgStart
 
@@ -16,10 +18,18 @@ IPC_MESSAGE_ROUTED3(ShellViewMsg_CaptureTextDump,
                     bool /* printing */,
                     bool /* recursive */)
 
+// Tells the render view to capture an image of the page. The render view
+// responds with a ShelLViewHostMsg_ImageDump.
+IPC_MESSAGE_ROUTED0(ShellViewMsg_CaptureImageDump)
+
 // Send a text dump of the WebContents to the render host.
 IPC_MESSAGE_ROUTED1(ShellViewHostMsg_TextDump,
                     std::string /* dump */)
 
+// Send an image dump of the WebContents to the render host.
+IPC_MESSAGE_ROUTED1(ShellViewHostMsg_ImageDump,
+                    SkBitmap /* image */)
+
 // The main frame of the render view finished loading.
 IPC_MESSAGE_ROUTED0(ShellViewHostMsg_DidFinishLoad)