Remove the 2-level input method system & InputMethodBridge.

ui/views/cocoa/bridged_native_widget.mm

Index: ui/views/cocoa/bridged_native_widget.mm
diff --git a/ui/views/cocoa/bridged_native_widget.mm b/ui/views/cocoa/bridged_native_widget.mm
index c5fa0a2c5ca7cb9376e0e21eead05b14dd0d8cd8..72c2a297170e97f3078662814f76d8bd023b58d9 100644
--- a/ui/views/cocoa/bridged_native_widget.mm
+++ b/ui/views/cocoa/bridged_native_widget.mm
@@ -25,8 +25,6 @@
 #include "ui/views/cocoa/tooltip_manager_mac.h"
 #import "ui/views/cocoa/views_nswindow_delegate.h"
 #import "ui/views/cocoa/widget_owner_nswindow_adapter.h"
-#include "ui/views/ime/input_method_bridge.h"
-#include "ui/views/ime/null_input_method.h"
 #include "ui/views/view.h"
 #include "ui/views/views_delegate.h"
 #include "ui/views/widget/native_widget_mac.h"
@@ -707,15 +705,10 @@ void BridgedNativeWidget::OnSizeConstraintsChanged() {
                                     shows_fullscreen_controls);
 }
 
-InputMethod* BridgedNativeWidget::CreateInputMethod() {
-  return new InputMethodBridge(this, GetHostInputMethod(), true);
-}
-
-ui::InputMethod* BridgedNativeWidget::GetHostInputMethod() {
+ui::InputMethod* BridgedNativeWidget::GetInputMethod() {
   if (!input_method_) {
-    // Delegate is NULL because Mac IME does not need DispatchKeyEventPostIME
-    // callbacks.
-    input_method_ = ui::CreateInputMethod(NULL, nil);
+    input_method_ = ui::CreateInputMethod(this, nil);
+    input_method_->OnFocus();

[tapted, 2015/06/29 04:57:21]

Can you add a comment about this line?

It seems out of place.. e.g. things like Textfield::SetReadOnly(..) call into
this, and the widget might not have focus then. I patched this in, and I see
text input breaks without this line.

The problem seems to be that the new version of
BridgedNativeWidget::OnDidChangeFocus(..) below will get a null TextInputClient
from InputMethodBase::GetTextInputClient()  (i.e. because
InputMethodBase::system_toplevel_window_focused_ is not yet set)

Is the problem that the Mac implementation is currently missing a call to
input_method_->OnFocus() when the widget gains focus? Is there a data race
somewhere? Do we need a different way to get the TextInputClient? (or perhaps
OnFocus really is the right thing to do -- I'm still wrapping my head around the
IME stuff :).

[Shu Chen, 2015/06/29 06:05:57]

ui::InputMethod::OnBlur() only gets called in DesktopNativeWidgetAura.
And for Mac, InputMethod::OnBlur() is never called.

So the OnFocus() call here is to make sure the InputMethod under Mac is "always
focused".
ChromeOS/Ash also uses such "always focused" mode.
Please refer to DisplayController::AddWindowTreeHostForDisplay().

[tapted, 2015/06/29 06:34:48]

Acknowledged. (we discussed this out of band - "always focused" mode is fine to
keep things simple for now. I'm going to follow-up to resolve the TODO with some
test coverage)

   }
   return input_method_.get();
 }
@@ -757,11 +750,12 @@ void BridgedNativeWidget::CreateLayer(ui::LayerType layer_type,
 ////////////////////////////////////////////////////////////////////////////////
 // BridgedNativeWidget, internal::InputMethodDelegate:
 
-void BridgedNativeWidget::DispatchKeyEventPostIME(const ui::KeyEvent& key) {
+bool BridgedNativeWidget::DispatchKeyEventPostIME(const ui::KeyEvent& key) {
   DCHECK(focus_manager_);
   native_widget_mac_->GetWidget()->OnKeyEvent(const_cast<ui::KeyEvent*>(&key));
   if (!key.handled())
     focus_manager_->OnKeyEvent(key);

[tapted, 2015/06/29 04:57:21]

BridgedContentView currently ignores the return value, but this should probably
be 

  return !focus_manager_->OnKeyEvent(key);

[Shu Chen, 2015/06/29 06:05:57]

Done.

+  return key.handled();
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -784,9 +778,12 @@ void BridgedNativeWidget::OnWillChangeFocus(View* focused_before,
 
 void BridgedNativeWidget::OnDidChangeFocus(View* focused_before,
                                            View* focused_now) {
-  ui::TextInputClient* input_client =
-      focused_now ? focused_now->GetTextInputClient() : NULL;
-  [bridged_view_ setTextInputClient:input_client];
+  ui::InputMethod* input_method =
+      native_widget_mac_->GetWidget()->GetInputMethod();
+  if (input_method) {
+    ui::TextInputClient* input_client = input_method->GetTextInputClient();
+    [bridged_view_ setTextInputClient:input_client];
+  }
 }
 
 ////////////////////////////////////////////////////////////////////////////////