Adding proper dragging behavior for L/R maximized windows.

ash/wm/workspace/frame_maximize_button.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ash/wm/workspace/frame_maximize_button.h"
 
 #include "ash/launcher/launcher.h"
 #include "ash/screen_ash.h"
 #include "ash/shell.h"
 #include "ash/wm/maximize_bubble_controller.h"
@@ skipping 535 matching lines @@
            frame_->GetWidget()->GetNativeWindow()))
     return FRAME_STATE_NONE;
   // The normal maximized test can be used.
   if (frame_->GetWidget()->IsMaximized())
     return FRAME_STATE_FULL;
   // For Left/right maximize we need to check the dimensions.
   gfx::Rect bounds = frame_->GetWidget()->GetWindowBoundsInScreen();
   gfx::Rect screen = gfx::Screen::GetDisplayMatching(bounds).work_area();
   if (bounds.width() < (screen.width() * kMinSnapSizePercent) / 100)
     return FRAME_STATE_NONE;
+  // We might still have a horizontally filled window at this point which we
+  // treat as no special state.
+  if (bounds.y() != screen.y() || bounds.height() != screen.height())
+    return FRAME_STATE_NONE;
+
   // We have to be in a maximize mode at this point.
-  DCHECK(bounds.y() == screen.y());
-  DCHECK(bounds.height() >= screen.height());
   if (bounds.x() == screen.x())
     return FRAME_STATE_SNAP_LEFT;
   if (bounds.right() == screen.right())
     return FRAME_STATE_SNAP_RIGHT;
   // If we come here, it is likely caused by the fact that the
   // "VerticalResizeDoubleClick" stored a restore rectangle. In that case
   // we allow all maximize operations (and keep the restore rectangle).
   return FRAME_STATE_NONE;
 }
 
 }  // namespace ash