MacViews: Implement InputMethodMac::CancelComposition.

ui/base/ime/input_method_mac.mm

Index: ui/base/ime/input_method_mac.mm
diff --git a/ui/base/ime/input_method_mac.mm b/ui/base/ime/input_method_mac.mm
index b03b1620e3f1758361d109a1794036172a841452..93b6db568f90c7046b65d17b995eb85575cf1833 100644
--- a/ui/base/ime/input_method_mac.mm
+++ b/ui/base/ime/input_method_mac.mm
@@ -4,6 +4,8 @@
 
 #include "ui/base/ime/input_method_mac.h"
 
+#include <Cocoa/Cocoa.h>

[tapted, 2016/10/25 02:57:57]

nit: import

+
 namespace ui {
 
 InputMethodMac::InputMethodMac(internal::InputMethodDelegate* delegate) {
@@ -27,6 +29,7 @@
 }
 
 void InputMethodMac::CancelComposition(const TextInputClient* client) {
+  [[NSTextInputContext currentInputContext] discardMarkedText];

[tapted, 2016/10/25 02:57:57]

Do we need

  if (!IsTextInputClientFocused(client))
    return;

the way Linux and Windows do?

They also do some GetEngine() stuff -- an IME reviewer might know if we need
something there too (but I suspect not).

[karandeepb, 2016/10/25 04:48:59]

Added the check.
 

 }
 
 bool InputMethodMac::IsCandidatePopupOpen() const {