arc: Implement Read and GetFileSize for ARC content file system

chrome/browser/ui/ash/chrome_shell_delegate.cc

Index: chrome/browser/ui/ash/chrome_shell_delegate.cc
diff --git a/chrome/browser/ui/ash/chrome_shell_delegate.cc b/chrome/browser/ui/ash/chrome_shell_delegate.cc
index 8697122de5a2c12a5fa4691d38fec20ab0e4b747..0aebfcdcf435ecfa611b3616dd2a9d4d6d260fee 100644
--- a/chrome/browser/ui/ash/chrome_shell_delegate.cc
+++ b/chrome/browser/ui/ash/chrome_shell_delegate.cc
@@ -29,6 +29,7 @@
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/chromeos/accessibility/accessibility_manager.h"
 #include "chrome/browser/chromeos/accessibility/magnification_manager.h"
+#include "chrome/browser/chromeos/arc/fileapi/arc_content_file_system_url_util.h"
 #include "chrome/browser/chromeos/background/ash_wallpaper_delegate.h"
 #include "chrome/browser/chromeos/display/display_configuration_observer.h"
 #include "chrome/browser/chromeos/display/display_preferences.h"
@@ -410,10 +411,17 @@ void ChromeShellDelegate::OpenUrlFromArc(const GURL& url) {
   if (!url.is_valid())
     return;
 
+  GURL url_to_open = url;
+  if (url.SchemeIs(url::kFileScheme) || url.SchemeIs(url::kContentScheme)) {
+    // Chrome cannot open this URL. Read the contents via ARC content file
+    // system with an external file URL.
+    url_to_open = arc::ArcUrlToExternalFileUrl(url_to_open);
+  }
+
   chrome::ScopedTabbedBrowserDisplayer displayer(
       ProfileManager::GetActiveUserProfile());
   chrome::AddSelectedTabWithURL(
-      displayer.browser(), url,
+      displayer.browser(), url_to_open,
       ui::PageTransitionFromInt(ui::PAGE_TRANSITION_LINK |
                                 ui::PAGE_TRANSITION_FROM_API));