Show composition window for IME-unaware PPAPI plugins on Windows.

ui/base/win/ime_input.cc

Index: ui/base/win/ime_input.cc
diff --git a/ui/base/win/ime_input.cc b/ui/base/win/ime_input.cc
index 2fa31082f411429bb21fc0e9a4e885275db1fefd..dcb4ef37968adb6202adfa105499dcf3f6e4977e 100644
--- a/ui/base/win/ime_input.cc
+++ b/ui/base/win/ime_input.cc
@@ -123,7 +123,8 @@ ImeInput::ImeInput()
       input_language_id_(LANG_USER_DEFAULT),
       is_composing_(false),
       system_caret_(false),
-      caret_rect_(-1, -1, 0, 0) {
+      caret_rect_(-1, -1, 0, 0),
+      use_composition_window_(false) {
 }
 
 ImeInput::~ImeInput() {
@@ -190,8 +191,10 @@ void ImeInput::DestroyImeWindow(HWND window_handle) {
 void ImeInput::MoveImeWindow(HWND window_handle, HIMC imm_context) {
   int x = caret_rect_.x();
   int y = caret_rect_.y();
+
   const int kCaretMargin = 1;
-  if (PRIMARYLANGID(input_language_id_) == LANG_CHINESE) {
+  if (!use_composition_window_ &&
+      PRIMARYLANGID(input_language_id_) == LANG_CHINESE) {
     // As written in a comment in ImeInput::CreateImeWindow(),
     // Chinese IMEs ignore function calls to ::ImmSetCandidateWindow()
     // when a user disables TSF (Text Service Framework) and CUAS (Cicero
@@ -216,6 +219,14 @@ void ImeInput::MoveImeWindow(HWND window_handle, HIMC imm_context) {
         break;
     }
   }
+  if (use_composition_window_) {
+    // Moves the composition text window.
+    COMPOSITIONFORM cf = {CFS_POINT, {x, y}};
+    ::ImmSetCompositionWindow(imm_context, &cf);
+    // Don't need to set the position of candidate window.
+    return;
+  }
+
   if (PRIMARYLANGID(input_language_id_) == LANG_KOREAN) {
     // Chinese IMEs and Japanese IMEs require the upper-left corner of
     // the caret to move the position of their candidate windows.
@@ -446,6 +457,10 @@ void ImeInput::UpdateCaretRect(HWND window_handle,
   }
 }
 
+void ImeInput::SetUseCompositionWindow(bool use_composition_window) {
+  use_composition_window_ = use_composition_window;
+}
+
 std::string ImeInput::GetInputLanguageName() const {
   const LCID locale_id = MAKELCID(input_language_id_, SORT_DEFAULT);
   // max size for LOCALE_SISO639LANGNAME and LOCALE_SISO3166CTRYNAME is 9.