MacViews: Fix behavior of move and select commands when selection direction changes.

ui/views/controls/textfield/textfield_unittest.cc

Index: ui/views/controls/textfield/textfield_unittest.cc
diff --git a/ui/views/controls/textfield/textfield_unittest.cc b/ui/views/controls/textfield/textfield_unittest.cc
index affd8dc47159c6d0273660df2bac6fd74e2163d5..c95d0c1a97646cd5dd48cd0a41f408370bc087e7 100644
--- a/ui/views/controls/textfield/textfield_unittest.cc
+++ b/ui/views/controls/textfield/textfield_unittest.cc
@@ -832,7 +832,13 @@ TEST_F(TextfieldTest, ControlAndSelectTest) {
   SendEndEvent(true);
   EXPECT_STR_EQ("two three", textfield_->GetSelectedText());
   SendHomeEvent(true);
+
+  // On Mac, the existing selection should be extended.
+#if defined(OS_MACOSX)
+  EXPECT_STR_EQ("ZERO two three", textfield_->GetSelectedText());
+#else
   EXPECT_STR_EQ("ZERO ", textfield_->GetSelectedText());
+#endif
 }
 
 TEST_F(TextfieldTest, InsertionDeletionTest) {