Remove base::Value::IsType

This change removes base::Value::IsType. It is superfluous and not part
of the new API. Existing usages are replaced by base::Value::is_* if
possible (e.g. |val.is_int()| instead of
|val.IsType(base::Value::Type::INTEGER)|). Otherwise, |type()| in
combination with operator== is used (e.g. |val.type() == type| instead
of |val.IsType(type)|).

Bug: 646113

Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.android:android_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_site_isolation;master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel
Change-Id: I62137317685800d1e7fedc77780d3acbbeb81b54
Reviewed-on: https://chromium-review.googlesource.com/659798
Reviewed-by: Brett Wilson <brettw@chromium.org>
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Commit-Queue: Jan Wilken Dörrie <jdoerrie@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#522988}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: e48b26a4fbf57528152e218356496f70bc54da5f
diff --git a/tools/gn/command_desc.cc b/tools/gn/command_desc.cc
index 6203d01..76ba21c 100644
--- a/tools/gn/command_desc.cc
+++ b/tools/gn/command_desc.cc
@@ -56,7 +56,7 @@
       PrintValue(&iter.value(), indentLevel + 1);
       iter.Advance();
     }
-  } else if (value->IsType(base::Value::Type::NONE)) {
+  } else if (value->is_none()) {
     OutputString(indent + "<null>\n");
   }
 }