Add kEditingModifier constant.

This constant represents the WebInputEvent::kMetaKey on Mac, and
WebInputEvent::kControlKey on other platforms. It can be checked against
web event modifiers to determine if the editing key (command on Mac
and control on other platforms) is held down.

BUG=59266

Change-Id: Ibdc67e56441fbf3855169fbf6ca1101884d86f38
Reviewed-on: https://chromium-review.googlesource.com/583855
Commit-Queue: Diana Gage <drgage@google.com>
Reviewed-by: Dave Tapuska <dtapuska@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#489464}
diff --git a/third_party/WebKit/Source/core/exported/WebPluginContainerImpl.cpp b/third_party/WebKit/Source/core/exported/WebPluginContainerImpl.cpp
index 0381a7d..187377a 100644
--- a/third_party/WebKit/Source/core/exported/WebPluginContainerImpl.cpp
+++ b/third_party/WebKit/Source/core/exported/WebPluginContainerImpl.cpp
@@ -109,6 +109,16 @@
 
 namespace blink {
 
+namespace {
+
+#if defined(OS_MACOSX)
+WebInputEvent::Modifiers kEditingModifier = WebInputEvent::kMetaKey;
+#else
+WebInputEvent::Modifiers kEditingModifier = WebInputEvent::kControlKey;
+#endif
+
+}  // namespace
+
 // Public methods --------------------------------------------------------------
 
 void WebPluginContainerImpl::AttachToLayout() {
@@ -823,15 +833,10 @@
 
   if (web_event.GetType() == WebInputEvent::kRawKeyDown ||
       web_event.GetType() == WebInputEvent::kKeyDown) {
-#if defined(OS_MACOSX)
     if ((web_event.GetModifiers() & WebInputEvent::kInputModifiers) ==
-            WebInputEvent::kMetaKey
-#else
-    if ((web_event.GetModifiers() & WebInputEvent::kInputModifiers) ==
-            WebInputEvent::kControlKey
-#endif
-        && (web_event.windows_key_code == VKEY_C ||
-            web_event.windows_key_code == VKEY_INSERT)
+            kEditingModifier &&
+        (web_event.windows_key_code == VKEY_C ||
+         web_event.windows_key_code == VKEY_INSERT)
         // Only copy if there's a selection, so that we only ever do this
         // for Pepper plugins that support copying.  Windowless NPAPI
         // plugins will get the event as before.