[OverlayWindow] Add custom WidgetDelegate.

Add a custom WidgetDelegate for OverlayWindowViews. This is used to
control more of the behaviour of OverlayWindow. This also adds a
placeholder window title string. Non-trivial beheaviour will be added
with more guidance from UX.

Bug: 726621
Change-Id: I7d6eae901248f90d8cbebc9bc4bd6e52aa7f714d
Reviewed-on: https://chromium-review.googlesource.com/722453
Commit-Queue: apacible <apacible@chromium.org>
Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
Cr-Commit-Position: refs/heads/master@{#509980}

chrome/app/generated_resources.grd

@@ -5904,6 +5904,11 @@ I don't think this site should be blocked!
         Turn on autoupdate
       </message>
 
+      <!-- Picture in Picture -->
+      <message name="IDS_PICTURE_IN_PICTURE_TITLE_TEXT" desc="Title of the picture in picture window. This appears in the system tray and window header.">
+        Picture in Picture
+      </message>
+
       <!-- Print -->
       <message name="IDS_DEFAULT_PRINT_DOCUMENT_TITLE" desc="Default title for a print document">
         Untitled Document

chrome/browser/ui/views/overlay/overlay_window_views.cc

@@ -4,13 +4,41 @@
 
 #include "chrome/browser/ui/views/overlay/overlay_window_views.h"
 
+#include "chrome/grit/generated_resources.h"
+#include "ui/base/l10n/l10n_util.h"
 #include "ui/views/widget/widget.h"
+#include "ui/views/widget/widget_delegate.h"
 
 // static
 std::unique_ptr<OverlayWindow> OverlayWindow::Create() {
   return base::WrapUnique(new OverlayWindowViews());
 }
 
+// OverlayWindow implementation of WidgetDelegate.
+class OverlayWindowWidgetDelegate : public views::WidgetDelegate {
+ public:
+  explicit OverlayWindowWidgetDelegate(views::Widget* widget)
+      : widget_(widget) {
+    DCHECK(widget_);
+  }
+  ~OverlayWindowWidgetDelegate() override = default;
+
+  // WidgetDelegate:
+  bool CanResize() const override { return true; }
+  ui::ModalType GetModalType() const override { return ui::MODAL_TYPE_SYSTEM; }
+  base::string16 GetWindowTitle() const override {
+    return l10n_util::GetStringUTF16(IDS_PICTURE_IN_PICTURE_TITLE_TEXT);
+  }
+  views::Widget* GetWidget() override { return widget_; }
+  const views::Widget* GetWidget() const override { return widget_; }
+
+ private:
+  // Owns OverlayWindowWidgetDelegate.
+  views::Widget* widget_;
+
+  DISALLOW_COPY_AND_ASSIGN(OverlayWindowWidgetDelegate);
+};
+
 OverlayWindowViews::OverlayWindowViews() {
   widget_.reset(new views::Widget());
 }
@@ -28,11 +56,11 @@ void OverlayWindowViews::Init() {
   params.keep_on_top = true;
   params.visible_on_all_workspaces = true;
 
+  // Set WidgetDelegate for more control over |widget_|.
+  params.delegate = new OverlayWindowWidgetDelegate(widget_.get());
+
   widget_->Init(params);
   widget_->Show();
-
-  // TODO(apacible): Set the WidgetDelegate for more control over behavior.
-  // http://crbug/726621
 }
 
 bool OverlayWindowViews::IsActive() const {