Redesigns the text input focus handling.

ui/views/controls/webview/webview.cc

Index: ui/views/controls/webview/webview.cc
diff --git a/ui/views/controls/webview/webview.cc b/ui/views/controls/webview/webview.cc
index 8da7e22ae11d704d44e81b4eb733fab4abcaa963..e04a5d0997743219cfbed88256d41dc39c73a453 100644
--- a/ui/views/controls/webview/webview.cc
+++ b/ui/views/controls/webview/webview.cc
@@ -14,6 +14,7 @@
 #include "ipc/ipc_message.h"
 #include "ui/accessibility/ax_enums.h"
 #include "ui/accessibility/ax_view_state.h"
+#include "ui/base/ui_base_switches_util.h"
 #include "ui/events/event.h"
 #include "ui/views/accessibility/native_view_accessibility.h"
 #include "ui/views/controls/native/native_view_host.h"
@@ -67,6 +68,7 @@ void WebView::SetWebContents(content::WebContents* replacement) {
     DCHECK(!is_embedding_fullscreen_widget_);
   }
   AttachWebContents();
+  NotifyMaybeTextInputClientChanged();
 }
 
 void WebView::SetEmbedFullscreenWidgetMode(bool enable) {
@@ -103,6 +105,25 @@ const char* WebView::GetClassName() const {
   return kViewClassName;
 }
 
+ui::TextInputClient* WebView::GetTextInputClient() {
+  // This function delegates the text input handling to the underlying
+  // content::RenderWidgetHostView.  So when the underlying RWHV is destroyed or
+  // replaced with another one, we have to notify the FocusManager through
+  // FocusManager::OnTextInputClientChanged() that the focused TextInputClient
+  // needs to be updated.
+

[msw, 2014/04/18 19:57:57]

nit: remove blank line

[Yuki, 2014/04/22 09:09:02]

Done.

+  if (switches::IsTextInputFocusManagerEnabled() &&
+      web_contents() && !web_contents()->IsBeingDestroyed()) {
+    content::RenderWidgetHostView* host_view =
+        is_embedding_fullscreen_widget_ ?
+        web_contents()->GetFullscreenRenderWidgetHostView() :
+        web_contents()->GetRenderWidgetHostView();
+    if (host_view)
+      return host_view->GetTextInputClient();
+  }
+  return NULL;
+}
+
 void WebView::OnBoundsChanged(const gfx::Rect& previous_bounds) {
   // In most cases, the holder is simply sized to fill this WebView's bounds.
   // Only WebContentses that are in fullscreen mode and being screen-captured
@@ -229,11 +250,16 @@ bool WebView::EmbedsFullscreenWidget() const {
 ////////////////////////////////////////////////////////////////////////////////
 // WebView, content::WebContentsObserver implementation:
 
+void WebView::RenderViewDeleted(content::RenderViewHost* render_view_host) {
+  NotifyMaybeTextInputClientChanged();
+}
+
 void WebView::RenderViewHostChanged(content::RenderViewHost* old_host,
                                     content::RenderViewHost* new_host) {
   FocusManager* const focus_manager = GetFocusManager();
   if (focus_manager && focus_manager->GetFocusedView() == this)
     OnFocus();
+  NotifyMaybeTextInputClientChanged();
 }
 
 void WebView::DidShowFullscreenWidget(int routing_id) {
@@ -309,6 +335,14 @@ void WebView::ReattachForFullscreenChange(bool enter_fullscreen) {
     // the same.  So, do not change attachment.
     OnBoundsChanged(bounds());
   }
+  NotifyMaybeTextInputClientChanged();
+}
+
+void WebView::NotifyMaybeTextInputClientChanged() {
+  // Update the TextInputClient as needed; see GetTextInputClient().
+  FocusManager* const focus_manager = GetFocusManager();

[msw, 2014/04/18 19:57:57]

nit: remove const.

[Yuki, 2014/04/22 09:09:02]

I'm okay to remove this const, but this is the style used in this file.  I just
followed the style used on other lines in this file.  Should I remove 'const'
from all the lines which call GetFocusManager()?

[msw, 2014/04/22 17:12:56]

Okay, the style guide says encourages putting const first (const FocusManager*
focus_manager), but does not require it; it's more important to be consistent
with the surrounding code. So, you can leave the const as-is here to be
consistent.

[Yuki, 2014/04/23 03:53:40]

Thanks.

Just FYI, const T* and T* const have different effects while const T* and T
const* have the same effect.

const T* p = The value pointed to is const.  The pointer is not const, so ++p is
valid.

T* const p = The pointer is const, so ++p is invalid.  But the value pointed to
is not const, so *p = x is valid.

const T* const p = Both of the value pointed to and the pointer itself are
const.  Either of ++p or *p = x are invalid.

[msw, 2014/04/23 04:50:12]

Right, I'm aware of the significance, but I believe using only one const
qualifier to protect against mutation of the object is more prevalent. Here,
|const FocusManager* const p| is viable, but it's just not frequently done (at
least in my experience). |FocusManager* const| is only used twice (and only in
this file), whereas the other form occurs four times (in view and widget).

+  if (focus_manager)
+    focus_manager->OnTextInputClientChanged(this);
 }
 
 content::WebContents* WebView::CreateWebContents(