Combine the WM_CHAR with WM_KEY* for key event flow.

win8/metro_driver/metro_driver_win7.cc

Index: win8/metro_driver/metro_driver_win7.cc
diff --git a/win8/metro_driver/metro_driver_win7.cc b/win8/metro_driver/metro_driver_win7.cc
index 3ace04caee0a06327e53b95281b2c12e2be42b5c..684b37a713273a486c41d82f361a4bea9cce8810 100644
--- a/win8/metro_driver/metro_driver_win7.cc
+++ b/win8/metro_driver/metro_driver_win7.cc
@@ -6,6 +6,8 @@
 #include <corewindow.h>
 #include <shobjidl.h>
 
+#include "base/base_switches.h"
+#include "base/command_line.h"
 #include "base/logging.h"
 #include "base/profiler/scoped_tracker.h"
 #include "ui/gfx/geometry/safe_integer_conversions.h"
@@ -371,8 +373,8 @@ class KeyEvent : public mswr::RuntimeClass<
     winui::Core::ICharacterReceivedEventArgs,
     winui::Core::IAcceleratorKeyEventArgs> {
  public:
-  KeyEvent(const MSG& msg)
-      : msg_(msg) {}
+  KeyEvent(const MSG& msg, bool was_key)
+      : msg_(msg), was_key_(was_key) {}
 
   // IKeyEventArgs implementation.
   HRESULT STDMETHODCALLTYPE
@@ -388,8 +390,8 @@ class KeyEvent : public mswr::RuntimeClass<
     key_status->ScanCode = (msg_.lParam >> 16) & 0x00FF;
     key_status->IsExtendedKey = (msg_.lParam & (1 << 24));
     key_status->IsMenuKeyDown = (msg_.lParam & (1 << 29));
-    key_status->WasKeyDown = (msg_.lParam & (1 << 30));
     key_status->IsKeyReleased = (msg_.lParam & (1 << 31));
+    key_status->WasKeyDown = was_key_;
     return S_OK;
   }
 
@@ -414,6 +416,7 @@ class KeyEvent : public mswr::RuntimeClass<
 
  private:
   MSG msg_;
+  bool was_key_;
 };
 
 // The following classes are the emulation of the WinRT system as exposed
@@ -462,8 +465,15 @@ class CoreDispatcherEmulation :
 
     MSG msg = {0};
     while((::GetMessage(&msg, NULL, 0, 0) != 0) && g_window_count > 0) {
-      ProcessInputMessage(msg);
-      ::TranslateMessage(&msg);
+      if (!base::CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kDisableMergeKeyCharEvents)) {
+        ::TranslateMessage(&msg);
+        ProcessInputMessage(msg);
+      } else {
+        // Preserve the old behavior when merge- key-char-events is disabled.
+        ProcessInputMessage(msg);
+        ::TranslateMessage(&msg);
+      }
       ::DispatchMessage(&msg);
     }
     // TODO(cpu): figure what to do with msg.WParam which we would normally
@@ -522,7 +532,7 @@ class CoreDispatcherEmulation :
 
   bool HandleSystemKeys(const MSG& msg) {
     mswr::ComPtr<winui::Core::IAcceleratorKeyEventArgs> event_args;
-    event_args = mswr::Make<KeyEvent>(msg);
+    event_args = mswr::Make<KeyEvent>(msg, true);
     accelerator_key_event_handler_->Invoke(this, event_args.Get());
     return true;
   }
@@ -913,8 +923,30 @@ class CoreWindowEmulation
     switch (msg.message) {
       case WM_KEYDOWN:
       case WM_KEYUP: {
+        if (!base::CommandLine::ForCurrentProcess()->HasSwitch(
+            switches::kDisableMergeKeyCharEvents)) {
+          // Combines 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 char_msg;
+          while (::PeekMessage(&char_msg, msg.hwnd, WM_CHAR, WM_DEADCHAR,
+                               PM_REMOVE)) {
+            if (char_msg.message == WM_DEADCHAR)
+              continue;
+            mswr::ComPtr<winui::Core::ICharacterReceivedEventArgs> char_args;
+            char_args = mswr::Make<KeyEvent>(char_msg, true);
+            character_received_handler_->Invoke(this, char_args.Get());
+          }
+        }
         mswr::ComPtr<winui::Core::IKeyEventArgs> event_args;
-        event_args = mswr::Make<KeyEvent>(msg);
+        event_args = mswr::Make<KeyEvent>(msg, true);
         KeyEventHandler* handler = NULL;
         if (msg.message == WM_KEYDOWN) {
           handler = key_down_handler_;
@@ -925,11 +957,9 @@ class CoreWindowEmulation
         break;
       }
 
-      case WM_CHAR:
-      case WM_DEADCHAR:
-      case WM_UNICHAR: {
+      case WM_CHAR: {
         mswr::ComPtr<winui::Core::ICharacterReceivedEventArgs> event_args;
-        event_args = mswr::Make<KeyEvent>(msg);
+        event_args = mswr::Make<KeyEvent>(msg, false);
         character_received_handler_->Invoke(this, event_args.Get());
         break;
       }