Add Clipboard GetSequenceNumber interface which allows us to version the data on the clipboard.

BUG=73478 
Review URL: http://codereview.chromium.org/7222016

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@90646 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 21 insertions, 0 deletions

diff --git a/ui/base/clipboard/clipboard.h b/ui/base/clipboard/clipboard.h
index 744f7a6..b9ae1fb 100644
--- a/ui/base/clipboard/clipboard.h
+++ b/ui/base/clipboard/clipboard.h
@@ -169,6 +169,11 @@ class Clipboard {
   // format is never controlled by the user.
   void ReadData(const std::string& format, std::string* result);
 
+  // Returns a sequence number which uniquely identifies clipboard state.
+  // This can be used to version the data on the clipboard and determine
+  // whether it has changed.
+  uint64 GetSequenceNumber();
+
   // Get format Identifiers for various types.
   static FormatType GetUrlFormatType();
   static FormatType GetUrlWFormatType();
diff --git a/ui/base/clipboard/clipboard_linux.cc b/ui/base/clipboard/clipboard_linux.cc
index 13cc759..718fed5 100644
--- a/ui/base/clipboard/clipboard_linux.cc
+++ b/ui/base/clipboard/clipboard_linux.cc
@@ -409,6 +409,13 @@ void Clipboard::ReadData(const std::string& format, std::string* result) {
   gtk_selection_data_free(data);
 }
 
+uint64 Clipboard::GetSequenceNumber() {
+  // TODO(cdn): implement this. For now this interface will advertise
+  // that the Linux clipboard never changes. That's fine as long as we
+  // don't rely on this signal.
+  return 0;
+}
+
 // static
 Clipboard::FormatType Clipboard::GetPlainTextFormatType() {
   return GdkAtomToString(GDK_TARGET_STRING);
diff --git a/ui/base/clipboard/clipboard_mac.mm b/ui/base/clipboard/clipboard_mac.mm
index eb89565..9f65e79 100644
--- a/ui/base/clipboard/clipboard_mac.mm
+++ b/ui/base/clipboard/clipboard_mac.mm
@@ -319,6 +319,11 @@ void Clipboard::ReadFiles(std::vector<FilePath>* files) const {
   }
 }
 
+uint64 Clipboard::GetSequenceNumber() {
+  NSPasteboard* pb = GetPasteboard();
+  return [pb changeCount];
+}
+
 // static
 Clipboard::FormatType Clipboard::GetUrlFormatType() {
   static const std::string type = base::SysNSStringToUTF8(NSURLPboardType);
diff --git a/ui/base/clipboard/clipboard_win.cc b/ui/base/clipboard/clipboard_win.cc
index eb4f34b..bada69b7 100644
--- a/ui/base/clipboard/clipboard_win.cc
+++ b/ui/base/clipboard/clipboard_win.cc
@@ -552,6 +552,10 @@ void Clipboard::ReadData(const std::string& format, std::string* result) {
   ::GlobalUnlock(data);
 }
 
+uint64 Clipboard::GetSequenceNumber() {
+  return ::GetClipboardSequenceNumber();
+}
+
 // static
 void Clipboard::ParseBookmarkClipboardFormat(const string16& bookmark,
                                              string16* title,