Ensure MimeHandlerView plugins load properly with long URLs

extensions/browser/api/mime_handler_private/mime_handler_private.cc

Index: extensions/browser/api/mime_handler_private/mime_handler_private.cc
diff --git a/extensions/browser/api/mime_handler_private/mime_handler_private.cc b/extensions/browser/api/mime_handler_private/mime_handler_private.cc
index 4b9c5e382d723600598d70f380760f4c3a89ceb5..13caee208f0557a23542b4848829c463f6668de1 100644
--- a/extensions/browser/api/mime_handler_private/mime_handler_private.cc
+++ b/extensions/browser/api/mime_handler_private/mime_handler_private.cc
@@ -7,6 +7,7 @@
 #include "base/strings/string_util.h"
 #include "content/public/browser/stream_handle.h"
 #include "content/public/browser/stream_info.h"
+#include "content/public/common/content_constants.h"
 #include "extensions/browser/guest_view/mime_handler_view/mime_handler_view_guest.h"
 #include "extensions/common/constants.h"
 #include "net/http/http_response_headers.h"
@@ -99,7 +100,18 @@ extensions::mime_handler::StreamInfoPtr TypeConverter<
   result->tab_id = stream.tab_id();
   const content::StreamInfo* info = stream.stream_info();
   result->mime_type = info->mime_type;
-  result->original_url = info->original_url.spec();
+
+  // If the URL is too long, mojo will give up on sending the URL. In these
+  // cases truncate it. Only data: URLs should ever really suffer this problem
+  // so only worry about those for now.
+  // TODO(raymes): This appears to be a bug in mojo somewhere. crbug.com/480099.
+  if (info->original_url.SchemeIs(url::kDataScheme) &&
+      info->original_url.spec().size() > content::kMaxURLDisplayChars) {
+    result->original_url = info->original_url.scheme() + ":";
+  } else {
+    result->original_url = info->original_url.spec();
+  }
+
   result->stream_url = info->handle->GetURL().spec();
   result->response_headers =
       extensions::CreateResponseHeadersMap(info->response_headers.get());