mac: Use more modern API for writing images to the pasteboard.

ui/base/clipboard/clipboard_mac.mm

Index: ui/base/clipboard/clipboard_mac.mm
diff --git a/ui/base/clipboard/clipboard_mac.mm b/ui/base/clipboard/clipboard_mac.mm
index f3a4c434704ca60926ab0cce3d0cf378cd9f347b..d45bcf2cc098f2e0c86a04ba3f1ca7e0bd51ced9 100644
--- a/ui/base/clipboard/clipboard_mac.mm
+++ b/ui/base/clipboard/clipboard_mac.mm
@@ -430,17 +430,11 @@ void ClipboardMac::WriteBookmark(const char* title_data,
 }
 
 void ClipboardMac::WriteBitmap(const SkBitmap& bitmap) {
+  NSPasteboard* pb = GetPasteboard();
+  [pb clearContents];
   NSImage* image = skia::SkBitmapToNSImageWithColorSpace(
       bitmap, base::mac::GetSystemColorSpace());
-  // An API to ask the NSImage to write itself to the clipboard comes in 10.6 :(
-  // For now, spit out the image as a TIFF.
-  NSPasteboard* pb = GetPasteboard();
-  [pb addTypes:[NSArray arrayWithObject:NSTIFFPboardType] owner:nil];
-  NSData* tiff_data = [image TIFFRepresentation];
-  LOG_IF(ERROR, tiff_data == NULL) << "Failed to allocate image for clipboard";
-  if (tiff_data) {
-    [pb setData:tiff_data forType:NSTIFFPboardType];
-  }
+  [pb writeObjects:@[ image ]];
 }
 
 void ClipboardMac::WriteData(const FormatType& format,