Implement declarativeContent API.

chrome/common/extensions/extension_messages.h

Index: chrome/common/extensions/extension_messages.h
diff --git a/chrome/common/extensions/extension_messages.h b/chrome/common/extensions/extension_messages.h
index 20504d7661ef87022e27f7ff8800d1063651742f..2f44d19460a07f86db6ac6034fc99dc97d0bb440 100644
--- a/chrome/common/extensions/extension_messages.h
+++ b/chrome/common/extensions/extension_messages.h
@@ -389,6 +389,13 @@ IPC_MESSAGE_ROUTED2(ExtensionMsg_AddMessageToConsole,
 // Notify the renderer that its window has closed.
 IPC_MESSAGE_ROUTED0(ExtensionMsg_AppWindowClosed)
 
+// Notify the renderer that an extension wants notifications when certain
+// searches match the active page.  This message replaces the old set of
+// searches, and triggers ExtensionHostMsg_OnWatchedPageChange messages from
+// each tab to keep the browser updated about changes.
+IPC_MESSAGE_CONTROL1(ExtensionMsg_WatchPages,
+                     std::vector<std::string> /* CSS selectors */)
+
 // Messages sent from the renderer to the browser.
 
 // A renderer sends this message when an extension process starts an API
@@ -571,3 +578,14 @@ IPC_MESSAGE_CONTROL1(ExtensionHostMsg_ResumeRequests, int /* route_id */)
 // Sent by the renderer when the draggable regions are updated.
 IPC_MESSAGE_ROUTED1(ExtensionHostMsg_UpdateDraggableRegions,
                     std::vector<extensions::DraggableRegion> /* regions */)
+
+// Notifies the browser process that a tab has started or stopped matching
+// certain conditions.  This message is sent in response to several events:
+//
+// * ExtensionMsg_WatchPages was received, updating the set of conditions.
+// * A new page is loaded.  This will be sent after ViewHostMsg_FrameNavigate.
+//   Currently this only fires for the main frame.
+// * Something changed on an existing frame causing the set of matching searches
+//   to change.
+IPC_MESSAGE_ROUTED1(ExtensionHostMsg_OnWatchedPageChange,
+                    std::vector<std::string> /* Matching CSS selectors */)