Implement Linux IME support

mojo/services/keyboard/interfaces/keyboard.mojom

Index: mojo/services/keyboard/interfaces/keyboard.mojom
diff --git a/mojo/services/keyboard/interfaces/keyboard.mojom b/mojo/services/keyboard/interfaces/keyboard.mojom
index 97942207a8ac08efdf7931d35b1d49500c9792f9..4921a20a66246a870483961f10f7e8e9923bce0e 100644
--- a/mojo/services/keyboard/interfaces/keyboard.mojom
+++ b/mojo/services/keyboard/interfaces/keyboard.mojom
@@ -5,6 +5,8 @@
 [DartPackage="mojo_services"]
 module keyboard;
 
+import "native_viewport/interfaces/native_viewport.mojom";
+
 struct CompletionData {
   int64 id;
   int32 position;
@@ -49,3 +51,10 @@ interface KeyboardService {
   SetText(string text);
   SetSelection(int32 start, int32 end);
 };
+
+[ServiceName="keyboard::KeyboardServiceFactory"]
+interface KeyboardServiceFactory {
+  CreateKeyboardService(
+      mojo.NativeViewportEventDispatcher& keyEventDispatcher,
+      KeyboardService& serviceRequest);
+};