[IME] Fix s_suppressNextKeypressEvent logic in WebViewImpl::setComposition().

Source/web/WebViewImpl.cpp

 /*
  * Copyright (C) 2011, 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 2286 matching lines @@
     // editable because JavaScript may delete a parent node of the composition
     // node. In this case, WebKit crashes while deleting texts from the parent
     // node, which doesn't exist any longer.
     RefPtrWillBeRawPtr<Range> range = inputMethodController.compositionRange();
     if (range) {
         Node* node = range->startContainer();
         if (!node || !node->isContentEditable())
             return false;
     }
 
-    // If we're not going to fire a keypress event, then the keydown event was
-    // canceled.  In that case, cancel any existing composition.
-    if (text.isEmpty() || m_suppressNextKeypressEvent) {
-        // A browser process sent an IPC message which does not contain a valid
-        // string, which means an ongoing composition has been canceled.
-        // If the ongoing composition has been canceled, replace the ongoing
-        // composition string with an empty string and complete it.
-        String emptyString;
-        Vector<CompositionUnderline> emptyUnderlines;
-        inputMethodController.setComposition(emptyString, emptyUnderlines, 0, 0);
+    // A keypress event is canceled. If an ongoing composition exists, then the
+    // keydown event should have arisen from a handled key (e.g., backspace).
+    // In this case we ignore the cancellation and continue; otherwise (no
+    // ongoing composition) we exit and signal success only for attempts to
+    // clear the composition.
+    if (m_suppressNextKeypressEvent && !inputMethodController.hasComposition())
         return text.isEmpty();
-    }
 
     // When the range of composition underlines overlap with the range between
     // selectionStart and selectionEnd, WebKit somehow won't paint the selection
     // at all (see InlineTextBox::paint() function in InlineTextBox.cpp).
     // But the selection range actually takes effect.
     inputMethodController.setComposition(String(text),
                            CompositionUnderlineVectorBuilder(underlines),
                            selectionStart, selectionEnd);
 
-    return inputMethodController.hasComposition();
+    return text.isEmpty() || inputMethodController.hasComposition();
 }
 
 bool WebViewImpl::confirmComposition()
 {
     return confirmComposition(DoNotKeepSelection);
 }
 
 bool WebViewImpl::confirmComposition(ConfirmCompositionBehavior selectionBehavior)
 {
     return confirmComposition(WebString(), selectionBehavior);
@@ skipping 2332 matching lines @@
     return mainFrameImpl()->frameView()->layoutSize().width() == m_size.width
         || (constraints.minimumScale == constraints.maximumScale && constraints.minimumScale != -1);
 }
 
 void WebViewImpl::forceNextWebGLContextCreationToFail()
 {
     WebGLRenderingContext::forceNextWebGLContextCreationToFail();
 }
 
 } // namespace blink