Workaround a nasty ibus issue.

chrome/browser/renderer_host/gtk_im_context_wrapper.cc

Index: chrome/browser/renderer_host/gtk_im_context_wrapper.cc
diff --git a/chrome/browser/renderer_host/gtk_im_context_wrapper.cc b/chrome/browser/renderer_host/gtk_im_context_wrapper.cc
index 0c2002cdb54774964d23fff864563ac3a7e668ae..0008ec96d5eb2d57828b0f70a3be6fe12f653afa 100644
--- a/chrome/browser/renderer_host/gtk_im_context_wrapper.cc
+++ b/chrome/browser/renderer_host/gtk_im_context_wrapper.cc
@@ -55,7 +55,10 @@ GtkIMContextWrapper::GtkIMContextWrapper(RenderWidgetHostViewGtk* host_view)
       preedit_selection_start_(0),
       preedit_selection_end_(0),
       is_preedit_changed_(false),
-      suppress_next_commit_(false) {
+      suppress_next_commit_(false),
+      last_key_code_(0),
+      last_key_was_up_(false),
+      last_key_filtered_no_result_(false) {
   DCHECK(context_);
   DCHECK(context_simple_);
 
@@ -158,11 +161,19 @@ void GtkIMContextWrapper::ProcessKeyEvent(GdkEventKey* event) {
   // RenderView::UnhandledKeyboardEvent() from processing it.
   // Otherwise unexpected result may occur. For example if it's a
   // Backspace key event, the browser may go back to previous page.
-  if (filtered)
+  // We just send all keyup events to the browser to avoid breaking the
+  // browser's MENU key function, which is actually the only keyup event
+  // handled in the browser.
+  if (filtered && event->type == GDK_KEY_PRESS)
     wke.skip_in_browser = true;
 
+  const int key_code = wke.windowsKeyCode;
+  const bool has_result = HasInputMethodResult();
+
   // Send filtered keydown event before sending IME result.
-  if (event->type == GDK_KEY_PRESS && filtered)
+  // In order to workaround http://crosbug.com/6582, we only send a filtered
+  // keydown event if it generated any input method result.
+  if (event->type == GDK_KEY_PRESS && filtered && has_result)
     ProcessFilteredKeyPressEvent(&wke);
 
   // Send IME results. In most cases, it's only available if the key event
@@ -182,13 +193,26 @@ void GtkIMContextWrapper::ProcessKeyEvent(GdkEventKey* event) {
   //
   // In this case, the input box will be in a strange state if keydown
   // Backspace is sent to webkit before commit "a" and preedit end.
-  ProcessInputMethodResult(event, filtered);
+  if (has_result)
+    ProcessInputMethodResult(event, filtered);
 
   // Send unfiltered keydown and keyup events after sending IME result.
-  if (event->type == GDK_KEY_PRESS && !filtered)
+  if (event->type == GDK_KEY_PRESS && !filtered) {
     ProcessUnfilteredKeyPressEvent(&wke);
-  else if (event->type == GDK_KEY_RELEASE)
-    host_view_->ForwardKeyboardEvent(wke);
+  } else if (event->type == GDK_KEY_RELEASE) {
+    // In order to workaround http://crosbug.com/6582, we need to suppress
+    // the keyup event if corresponding keydown event was suppressed, or
+    // the last key event was a keyup event with the same keycode.
+    const bool suppress = (last_key_code_ == key_code) &&
+        (last_key_was_up_ || last_key_filtered_no_result_);
+
+    if (!suppress)
+      host_view_->ForwardKeyboardEvent(wke);
+  }
+
+  last_key_code_ = key_code;
+  last_key_was_up_ = (event->type == GDK_KEY_RELEASE);
+  last_key_filtered_no_result_ = (filtered && !has_result);
 }
 
 void GtkIMContextWrapper::UpdateInputMethodState(WebKit::WebTextInputType type,
@@ -229,6 +253,10 @@ void GtkIMContextWrapper::OnFocusIn() {
   // GtkIMContext object correctly later when IME is enabled by WebKit.
   is_focused_ = true;
 
+  last_key_code_ = 0;
+  last_key_was_up_ = false;
+  last_key_filtered_no_result_ = false;
+
   // Notify the GtkIMContext object of this focus-in event only if IME is
   // enabled by WebKit.
   if (is_enabled_)
@@ -322,7 +350,7 @@ void GtkIMContextWrapper::CancelComposition() {
   is_in_key_event_handler_ = false;
 }
 
-bool GtkIMContextWrapper::NeedCommitByForwardingCharEvent() {
+bool GtkIMContextWrapper::NeedCommitByForwardingCharEvent() const {
   // If there is no composition text and has only one character to be
   // committed, then the character will be send to webkit as a Char event
   // instead of a confirmed composition text.
@@ -331,6 +359,10 @@ bool GtkIMContextWrapper::NeedCommitByForwardingCharEvent() {
   return !is_composing_text_ && commit_text_.length() == 1;
 }
 
+bool GtkIMContextWrapper::HasInputMethodResult() const {
+  return commit_text_.length() || is_preedit_changed_;
+}
+
 void GtkIMContextWrapper::ProcessFilteredKeyPressEvent(
     NativeWebKeyboardEvent* wke) {
   // If IME has filtered this event, then replace virtual key code with