Support Arc, crostini, and Plugin VM in drag drop FileHelper

The current code in FileHelper assumes all windows are Arc. We now
check the source and target aura::Window to detect and do the
appropriate path translations and share files when necessary with
crostini/pluginvm.

For example, when crostini is the drag source, we will convert paths
such as:

 <homedir>/file => /media/fuse/crostini_<hash>_termina_penguin/file

And do the opposite translation when crostini is the drop target.

We also convert paths and share files such as:

 <cryptohome>/MyFiles/file => /mnt/chromeos/MyFiles/file
 /media/removable/MyUSB => /mnt/chromeos/removable/MyUSB

For PluginVM, the translation is

 <cryptohome>/MyFiles/file => //ChromeOS/MyFiles/file
 /media/removable/MyUSB => //ChromeOS/removable/MyUSB

Bug: 1144138
Change-Id: I2bb38336537acf13c4797374d6dabe6e518d689e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2517346
Commit-Queue: Joel Hockey <joelhockey@chromium.org>
Reviewed-by: Jason Lin <lxj@google.com>
Reviewed-by: Mitsuru Oshima <oshima@chromium.org>
Cr-Commit-Position: refs/heads/master@{#827956}

chrome/browser/chromeos/crostini/crostini_util.cc

@@ -6,6 +6,7 @@
 
 #include <utility>
 
+#include "ash/public/cpp/app_types.h"
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/callback_helpers.h"
@@ -44,6 +45,7 @@
 #include "components/prefs/pref_service.h"
 #include "components/user_manager/user.h"
 #include "google_apis/gaia/gaia_auth_util.h"
+#include "ui/aura/client/aura_constants.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/base/l10n/time_format.h"
 
@@ -574,4 +576,10 @@ const ContainerId& DefaultContainerId() {
       kCrostiniDefaultVmName, kCrostiniDefaultContainerName);
   return *container_id;
 }
+
+bool IsCrostiniWindow(aura::Window* window) {
+  return window->GetProperty(aura::client::kAppType) ==
+         static_cast<int>(ash::AppType::CROSTINI_APP);
+}
+
 }  // namespace crostini

chrome/browser/chromeos/crostini/crostini_util.h

@@ -18,6 +18,10 @@
 #include "storage/browser/file_system/file_system_url.h"
 #include "third_party/abseil-cpp/absl/types/variant.h"
 
+namespace aura {
+class Window;
+}  // namespace aura
+
 namespace base {
 class FilePath;
 }  // namespace base
@@ -205,6 +209,8 @@ void UpdateContainerPref(Profile* profile,
 
 const ContainerId& DefaultContainerId();
 
+bool IsCrostiniWindow(aura::Window* window);
+
 }  // namespace crostini
 
 #endif  // CHROME_BROWSER_CHROMEOS_CROSTINI_CROSTINI_UTIL_H_