While screencasting a tab, do not disable rendering updates while hidden.

chrome/browser/ui/views/tabs/tab_drag_controller.cc

Index: chrome/browser/ui/views/tabs/tab_drag_controller.cc
diff --git a/chrome/browser/ui/views/tabs/tab_drag_controller.cc b/chrome/browser/ui/views/tabs/tab_drag_controller.cc
index c3980924258555be4adeb146fc11318f6f8da8a6..79ce2d21fd85313d683d31ecac637e332c877638 100644
--- a/chrome/browser/ui/views/tabs/tab_drag_controller.cc
+++ b/chrome/browser/ui/views/tabs/tab_drag_controller.cc
@@ -489,6 +489,9 @@ void TabDragController::Drag(const gfx::Point& point_in_screen) {
       return;  // User hasn't dragged far enough yet.
 
     started_drag_ = true;
+    // Prevent the WebContents HWND from being hidden by any of the model
+    // operations performed during the drag.
+    source_dragged_contents()->SetCapturingContents(true);
     SaveFocus();
     Attach(source_tabstrip_, gfx::Point());
     if (detach_into_browser_ && static_cast<int>(drag_data_.size()) ==
@@ -1135,9 +1138,6 @@ void TabDragController::Attach(TabStrip* attached_tabstrip,
         drag_data_[i].contents->SetDelegate(NULL);
         drag_data_[i].original_delegate = NULL;
       }
-
-      // Return the WebContents to normalcy.
-      source_dragged_contents()->SetCapturingContents(false);
     }
 
     // Inserting counts as a move. We don't want the tabs to jitter when the
@@ -1223,11 +1223,6 @@ void TabDragController::Detach(ReleaseCapture release_capture) {
 
   mouse_move_direction_ = kMovedMouseLeft | kMovedMouseRight;
 
-  // Prevent the WebContents HWND from being hidden by any of the model
-  // operations performed during the drag.
-  if (!detach_into_browser_)
-    source_dragged_contents()->SetCapturingContents(true);
-
   std::vector<gfx::Rect> drag_bounds = CalculateBoundsForDraggedTabs(0);
   TabStripModel* attached_model = GetModel(attached_tabstrip_);
   std::vector<TabRendererData> tab_data;
@@ -1605,6 +1600,7 @@ void TabDragController::EndDragImpl(EndDragType type) {
     // enough to trigger a drag.
     if (started_drag_) {
       RestoreFocus();
+      source_dragged_contents()->SetCapturingContents(false);
       if (type == CANCELED)
         RevertDrag();
       else