[CCA] Hide maximize button for intent instance under tablet mode

Since the maximize button under tablet mode does not work.

Bug: b/175322338
Test: Manually
Change-Id: I9e8f21c81b33d5e964f95e2fc259e88eea8bcdef
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2622365
Auto-Submit: Wei Lee <wtlee@chromium.org>
Reviewed-by: Shik Chen <shik@chromium.org>
Commit-Queue: Shik Chen <shik@chromium.org>
Commit-Queue: Wei Lee <wtlee@chromium.org>
Cr-Commit-Position: refs/heads/master@{#842423}

chrome/browser/chromeos/web_applications/chrome_camera_app_ui_delegate.cc

@@ -6,6 +6,7 @@
 
 #include <vector>
 
+#include "ash/public/cpp/tablet_mode.h"
 #include "base/files/file_path.h"
 #include "base/system/sys_info.h"
 #include "chrome/browser/apps/app_service/app_service_proxy.h"
@@ -53,7 +54,7 @@ ui::ModalType ChromeCameraAppUIDelegate::CameraAppDialog::GetDialogModalType()
 }
 
 bool ChromeCameraAppUIDelegate::CameraAppDialog::CanMaximizeDialog() const {
-  return true;
+  return !ash::TabletMode::Get()->InTabletMode();
 }
 
 void ChromeCameraAppUIDelegate::CameraAppDialog::GetDialogSize(