updating Input field value by script should reset IME composition.

third_party/WebKit/Source/core/editing/InputMethodController.cpp

Index: third_party/WebKit/Source/core/editing/InputMethodController.cpp
diff --git a/third_party/WebKit/Source/core/editing/InputMethodController.cpp b/third_party/WebKit/Source/core/editing/InputMethodController.cpp
index 57512ea51f33318b7f07149afe12fd579b00d387..c161b8cd6533de68460d74e1f8eb994203c72961 100644
--- a/third_party/WebKit/Source/core/editing/InputMethodController.cpp
+++ b/third_party/WebKit/Source/core/editing/InputMethodController.cpp
@@ -558,6 +558,32 @@ void InputMethodController::CancelComposition() {
   DispatchCompositionEndEvent(GetFrame(), g_empty_string);
 }
 
+void InputMethodController::CancelCompositionIfSelectionIsInvalid() {
+  if (!has_composition_)
+    return;
+
+  /*if (composition_range_)
+    LOG(INFO) << composition_range_->toString();
+  else
+    LOG(INFO) << "null range";
+  if (!HasComposition() || GetEditor().PreventRevealSelection())
+         return;
+  
+       // Check if selection start and selection end are valid.	
+  FrameSelection& selection = GetFrame().Selection();
+     if (selection.IsAvailable() && !composition_range_->collapsed()) {
+       const SelectionInDOMTree& selection_in_dom = selection.GetSelectionInDOMTree();
+         if (selection_in_dom.Base().CompareTo(composition_range_->StartPosition()) >= 0 &&
+           selection_in_dom.Extent().CompareTo(composition_range_->EndPosition()) <= 0)
+             return;
+    
+  }*/
+  
+       Clear();
+    GetFrame().GetChromeClient().DidCancelCompositionOnSelectionChange();
+  
+}
+
 void InputMethodController::SetComposition(
     const String& text,
     const Vector<CompositionUnderline>& underlines,