Add FakeClipboard implementation for unit tests.

ui/base/clipboard/clipboard_android.cc

Index: ui/base/clipboard/clipboard_android.cc
diff --git a/ui/base/clipboard/clipboard_android.cc b/ui/base/clipboard/clipboard_android.cc
index 8b25b7cc01448124b71c2fff1824d1e4e3f9d65f..067f75268dcfcf8147c8625ad70954a3cd132b44 100644
--- a/ui/base/clipboard/clipboard_android.cc
+++ b/ui/base/clipboard/clipboard_android.cc
@@ -198,6 +198,10 @@ Clipboard::FormatType Clipboard::FormatType::Deserialize(
   return FormatType(serialization);
 }
 
+bool Clipboard::FormatType::operator<(const FormatType& other) const {
+  return data_ < other.data_;
+}
+
 bool Clipboard::FormatType::Equals(const FormatType& other) const {
   return data_ == other.data_;
 }
@@ -272,7 +276,7 @@ ClipboardAndroid::~ClipboardAndroid() {
   DCHECK(CalledOnValidThread());
 }
 
-uint64 ClipboardAndroid::GetSequenceNumber(ClipboardType /* type */) {
+uint64 ClipboardAndroid::GetSequenceNumber(ClipboardType /* type */) const {
   DCHECK(CalledOnValidThread());
   // TODO: implement this. For now this interface will advertise
   // that the clipboard never changes. That's fine as long as we