Combine the WM_CHAR with WM_KEY* for key event flow.

ui/base/ime/input_method_win.cc

Index: ui/base/ime/input_method_win.cc
diff --git a/ui/base/ime/input_method_win.cc b/ui/base/ime/input_method_win.cc
index 7db88b6298a3aba4b56d8eff5902250e1a2f00de..33de60cd445b25a1de89da760949b06afdd970c6 100644
--- a/ui/base/ime/input_method_win.cc
+++ b/ui/base/ime/input_method_win.cc
@@ -32,8 +32,7 @@ InputMethodWin::InputMethodWin(internal::InputMethodDelegate* delegate,
       accept_carriage_return_(false),
       enabled_(false),
       is_candidate_popup_open_(false),
-      composing_window_handle_(NULL),
-      suppress_next_char_(false) {
+      composing_window_handle_(NULL) {
   SetDelegate(delegate);
 }
 
@@ -104,9 +103,38 @@ void InputMethodWin::DispatchKeyEvent(ui::KeyEvent* event) {
     return;
   }
 
+  std::vector<MSG> char_msgs;
   const base::NativeEvent& native_key_event = event->native_event();
+  // Peek & remove the following messages in the message queue.
+  //  - WM_CHAR (0x0102)
+  //  - WM_DEADCHAR (0x0103)
+  //  - WM_SYSCHAR (0x0106)
+  //  - WM_SYSDEADCHAR (0x0107)
+  // And only process WM_CHAR & WM_SYSCHAR message in browser.
+  // This is to combine the WM_KEY* and WM_CHAR messages in the event
+  // processing flow which is necessary to let Chrome IME extension to process
+  // the key event and perform corresponding IME actions.
+  // Chrome IME extension may wants to consume certain key events based on
+  // the character information of WM_CHAR messages. Holding WM_KEY* messages
+  // until WM_CHAR is processed by the IME extension is not feasible because
+  // there is no way to know wether there will or not be a WM_CHAR following
+  // the WM_KEY*.
+  // Chrome never handles dead chars so it is safe to remove/ignore
+  // WM_*DEADCHAR messages.
+  MSG msg;
+  while (::PeekMessage(&msg, native_key_event.hwnd, WM_CHAR, WM_DEADCHAR,
+                       PM_REMOVE)) {
+    if (msg.message == WM_CHAR)
+      char_msgs.push_back(msg);
+  }
+  while (::PeekMessage(&msg, native_key_event.hwnd, WM_SYSCHAR, WM_SYSDEADCHAR,
+                       PM_REMOVE)) {
+    if (msg.message == WM_SYSCHAR)
+      char_msgs.push_back(msg);
+  }
+
+  BOOL handled = FALSE;
   if (native_key_event.message == WM_CHAR) {
-    BOOL handled;
     OnChar(native_key_event.hwnd, native_key_event.message,
            native_key_event.wParam, native_key_event.lParam, &handled);
     if (handled)
@@ -137,8 +165,15 @@ void InputMethodWin::DispatchKeyEvent(ui::KeyEvent* event) {
   }
 
   ui::EventDispatchDetails details = DispatchKeyEventPostIME(event);
-  if (!details.dispatcher_destroyed)
-    suppress_next_char_ = event->stopped_propagation();
+  if (details.dispatcher_destroyed || details.target_destroyed ||
+      event->stopped_propagation()) {
+    return;
+  }
+
+  for (size_t i = 0; i < char_msgs.size(); ++i) {
+    msg = char_msgs[i];
+    OnChar(msg.hwnd, msg.message, msg.wParam, msg.lParam, &handled);
+  }
 }
 
 void InputMethodWin::OnTextInputTypeChanged(const TextInputClient* client) {
@@ -224,11 +259,6 @@ LRESULT InputMethodWin::OnChar(HWND window_handle,
 
   *handled = TRUE;
 
-  if (suppress_next_char_) {
-    suppress_next_char_ = false;
-    return 0;
-  }
-
   // We need to send character events to the focused text input client event if
   // its text input type is ui::TEXT_INPUT_TYPE_NONE.
   if (GetTextInputClient()) {
@@ -587,10 +617,6 @@ bool InputMethodWin::IsWindowFocused(const TextInputClient* client) const {
 
 void InputMethodWin::DispatchFabricatedKeyEvent(ui::KeyEvent* event) {
   if (event->is_char()) {
-    if (suppress_next_char_) {
-      suppress_next_char_ = false;
-      return;
-    }
     if (GetTextInputClient()) {
       GetTextInputClient()->InsertChar(
           static_cast<base::char16>(event->key_code()),