Add UMA statistics to the clipboard

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 89febe7f981f85699b45347ea1d2d8c77b770e81..99a24a68e12811c84dd5fe4c35cdbc94798e6bd3 100644
--- a/ui/base/clipboard/clipboard_mac.mm
+++ b/ui/base/clipboard/clipboard_mac.mm
@@ -293,6 +293,7 @@ void Clipboard::ReadAvailableTypes(Clipboard::Buffer buffer,
 void Clipboard::ReadText(Clipboard::Buffer buffer, string16* result) const {
   DCHECK(CalledOnValidThread());
   DCHECK_EQ(buffer, BUFFER_STANDARD);
+  ReportAction(buffer, READ_TEXT);
   NSPasteboard* pb = GetPasteboard();
   NSString* contents = [pb stringForType:NSStringPboardType];
 
@@ -305,6 +306,7 @@ void Clipboard::ReadAsciiText(Clipboard::Buffer buffer,
                               std::string* result) const {
   DCHECK(CalledOnValidThread());
   DCHECK_EQ(buffer, BUFFER_STANDARD);
+  ReportAction(buffer, READ_TEXT);
   NSPasteboard* pb = GetPasteboard();
   NSString* contents = [pb stringForType:NSStringPboardType];
 
@@ -348,6 +350,7 @@ void Clipboard::ReadHTML(Clipboard::Buffer buffer, string16* markup,
 void Clipboard::ReadRTF(Buffer buffer, std::string* result) const {
   DCHECK(CalledOnValidThread());
   DCHECK_EQ(buffer, BUFFER_STANDARD);
+  ReportAction(buffer, READ_TEXT);
 
   return ReadData(GetRtfFormatType(), result);
 }