Fix the white flicker of the keyboard overlay when it first appearing.

chrome/browser/ui/views/keyboard_overlay_delegate.cc

Index: chrome/browser/ui/views/keyboard_overlay_delegate.cc
diff --git a/chrome/browser/ui/views/keyboard_overlay_delegate.cc b/chrome/browser/ui/views/keyboard_overlay_delegate.cc
index 56bcd6dab69a0441ad3b9b42ebc8e7d2fabf94a9..78445374feaeb16f0440d5c1622cdbfbefcf2364 100644
--- a/chrome/browser/ui/views/keyboard_overlay_delegate.cc
+++ b/chrome/browser/ui/views/keyboard_overlay_delegate.cc
@@ -6,9 +6,14 @@
 
 #include <algorithm>
 
+#include "base/bind.h"
+#include "base/memory/weak_ptr.h"
 #include "base/utf_string_conversions.h"
+#include "base/values.h"
 #include "chrome/browser/ui/views/web_dialog_view.h"
 #include "chrome/common/url_constants.h"
+#include "content/public/browser/web_ui.h"
+#include "content/public/browser/web_ui_message_handler.h"
 #include "googleurl/src/gurl.h"
 #include "grit/generated_resources.h"
 #include "ui/base/l10n/l10n_util.h"
@@ -24,6 +29,36 @@ const int kBaseWidth = 1252;
 const int kBaseHeight = 516;
 const int kHorizontalMargin = 28;
 
+// A message handler for detecting the timing when the web contents is painted.
+class PaintMessageHandler
+    : public WebUIMessageHandler,
+      public base::SupportsWeakPtr<PaintMessageHandler> {
+ public:
+  explicit PaintMessageHandler(views::Widget* widget) : widget_(widget) {}
+  virtual ~PaintMessageHandler() {}
+
+  // WebUIMessageHandler implementation.
+  virtual void RegisterMessages() OVERRIDE;
+
+ private:
+  void DidPaint(const ListValue* args);
+
+  views::Widget* widget_;
+
+  DISALLOW_COPY_AND_ASSIGN(PaintMessageHandler);
+};
+
+void PaintMessageHandler::RegisterMessages() {
+  web_ui()->RegisterMessageCallback(
+      "didPaint",
+      base::Bind(&PaintMessageHandler::DidPaint, base::Unretained(this)));
+}
+
+void PaintMessageHandler::DidPaint(const ListValue* args) {
+  // Show the widget after the web content has been painted.
+  widget_->Show();
+}
+
 }  // namespace
 
 KeyboardOverlayDelegate::KeyboardOverlayDelegate(const string16& title)
@@ -34,6 +69,29 @@ KeyboardOverlayDelegate::KeyboardOverlayDelegate(const string16& title)
 KeyboardOverlayDelegate::~KeyboardOverlayDelegate() {
 }
 
+void KeyboardOverlayDelegate::Show(WebDialogView* view) {
+  view_ = view;
+
+  views::Widget* widget = new views::Widget;
+  views::Widget::InitParams params(
+      views::Widget::InitParams::TYPE_WINDOW_FRAMELESS);
+  params.delegate = view;
+  widget->Init(params);
+
+  // Show the widget at the bottom of the work area.
+  gfx::Size size;
+  GetDialogSize(&size);
+  const gfx::Rect& rect = gfx::Screen::GetMonitorNearestWindow(
+      widget->GetNativeView()).work_area();
+  gfx::Rect bounds((rect.width() - size.width()) / 2,
+                   rect.height() - size.height(),
+                   size.width(),
+                   size.height());
+  widget->SetBounds(bounds);
+
+  // The widget will be shown when the web contents gets ready to display.
+}
+
 ui::ModalType KeyboardOverlayDelegate::GetDialogModalType() const {
   return ui::MODAL_TYPE_SYSTEM;
 }
@@ -49,6 +107,7 @@ GURL KeyboardOverlayDelegate::GetDialogContentURL() const {
 
 void KeyboardOverlayDelegate::GetWebUIMessageHandlers(
     std::vector<WebUIMessageHandler*>* handlers) const {
+  handlers->push_back(new PaintMessageHandler(view_->GetWidget()));
 }
 
 void KeyboardOverlayDelegate::GetDialogSize(