Pass mime type values as file dialog accept filters (see #3314)

File dialogs that specify mime type (e.g. "image/*") accept filters will pass
those values unchanged to the OnFileDialog |accept_filters| parameter. The
default dialog implementation will show those filters in addition to a combined
"Custom Files" filter. This is a change from preexisting Google Chrome
behavior where only the combined "Custom Files" filter is displayed, and
restores CEF behavior that existed prior to 2ea7459a89.

Document the fact that OnFileDialog may be called twice, once before MIME type
expansion and once afterwards.

Add new OnFileDialog |accept_extensions| and |accept_descriptions| parameters
for MIME type extensions and descriptions.

Details: This change adds a SelectFileDialog::FileTypeInfo::extension_mimetypes
member and improves the logic in FileSelectHelper::GetFileTypesFromAcceptType
and file_dialog_manager.cc SelectFileToFileChooserParams to support recall of
the source mime type when populating the FileChooserParams structure.

To test:
- Run `ceftests --gtest_filter=DialogTest.*`
- Run `cefclient --url=https://tests/dialogs`

tests/cefclient/browser/dialog_handler_gtk.cc

@@ -7,11 +7,13 @@
 #include <libgen.h>
 #include <sys/stat.h>
 
+#include "include/base/cef_logging.h"
 #include "include/cef_browser.h"
 #include "include/cef_parser.h"
 #include "include/wrapper/cef_helpers.h"
 #include "tests/cefclient/browser/root_window.h"
 #include "tests/cefclient/browser/util_gtk.h"
+#include "tests/shared/common/string_util.h"
 
 namespace client {
 
@@ -49,11 +51,14 @@ std::string GetDescriptionFromMimeType(const std::string& mime_type) {
     }
   }
 
+  LOG(WARNING) << "Unrecognized mime type: " << mime_type;
   return std::string();
 }
 
 void AddFilters(GtkFileChooser* chooser,
                 const std::vector<CefString>& accept_filters,
+                const std::vector<CefString>& accept_extensions,
+                const std::vector<CefString>& accept_descriptions,
                 bool include_all_files,
                 std::vector<GtkFileFilter*>* filters) {
   bool has_filter = false;
@@ -64,33 +69,13 @@ void AddFilters(GtkFileChooser* chooser,
       continue;
     }
 
-    std::vector<std::string> extensions;
-    std::string description;
-
-    size_t sep_index = filter.find('|');
-    if (sep_index != std::string::npos) {
-      // Treat as a filter of the form "Filter Name|.ext1;.ext2;.ext3".
-      description = filter.substr(0, sep_index);
-
-      const std::string& exts = filter.substr(sep_index + 1);
-      size_t last = 0;
-      size_t size = exts.size();
-      for (size_t i = 0; i <= size; ++i) {
-        if (i == size || exts[i] == ';') {
-          std::string ext(exts, last, i - last);
-          if (!ext.empty() && ext[0] == '.') {
-            extensions.push_back(ext);
-          }
-          last = i + 1;
-        }
-      }
-    } else if (filter[0] == '.') {
-      // Treat as an extension beginning with the '.' character.
-      extensions.push_back(filter);
-    } else {
-      // Otherwise convert mime type to one or more extensions.
-      description = GetDescriptionFromMimeType(filter);
+    // Extensions and descriptions may be provided.
+    std::vector<std::string> extensions =
+        AsciiStrSplit(accept_extensions[j], ';');
+    std::string description = accept_descriptions[j];
 
+    if (extensions.empty()) {
+      // Try to convert mime type to one or more extensions.
       std::vector<CefString> ext;
       CefGetExtensionsForMimeType(filter, ext);
       for (size_t x = 0; x < ext.size(); ++x) {
@@ -102,6 +87,10 @@ void AddFilters(GtkFileChooser* chooser,
       continue;
     }
 
+    if (description.empty() && filter[0] != '.') {
+      description = GetDescriptionFromMimeType(filter);
+    }
+
     GtkFileFilter* gtk_filter = gtk_file_filter_new();
 
     std::string ext_str;
@@ -154,6 +143,24 @@ GtkWindow* GetWindow(CefRefPtr<CefBrowser> browser) {
   return nullptr;
 }
 
+// Returns true if |accept_filters| contains a MIME type value without matching
+// extensions in |accept_extensions|.
+bool MissingMimeTypeData(const std::vector<CefString>& accept_filters,
+                         const std::vector<CefString>& accept_extensions) {
+  if (accept_filters.empty()) {
+    return false;
+  }
+
+  for (size_t i = 0; i < accept_filters.size(); ++i) {
+    const std::string& filter = accept_filters[i];
+    if (filter[0] != '.' && accept_extensions[i].empty()) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
 }  // namespace
 
 ClientDialogHandlerGtk::ClientDialogHandlerGtk() : gtk_dialog_(nullptr) {}
@@ -164,8 +171,17 @@ bool ClientDialogHandlerGtk::OnFileDialog(
     const CefString& title,
     const CefString& default_file_path,
     const std::vector<CefString>& accept_filters,
+    const std::vector<CefString>& accept_extensions,
+    const std::vector<CefString>& accept_descriptions,
     CefRefPtr<CefFileDialogCallback> callback) {
   CEF_REQUIRE_UI_THREAD();
+  DCHECK(accept_filters.size() == accept_extensions.size() ==
+         accept_descriptions.size());
+
+  if (MissingMimeTypeData(accept_filters, accept_extensions)) {
+    // Wait for the 2nd call that provides MIME type data.
+    return false;
+  }
 
   OnFileDialogParams params;
   params.browser = browser;
@@ -173,6 +189,8 @@ bool ClientDialogHandlerGtk::OnFileDialog(
   params.title = title;
   params.default_file_path = default_file_path;
   params.accept_filters = accept_filters;
+  params.accept_extensions = accept_extensions;
+  params.accept_descriptions = accept_descriptions;
   params.callback = callback;
 
   GetWindowAndContinue(
@@ -309,7 +327,9 @@ void ClientDialogHandlerGtk::OnFileDialogContinue(
   }
 
   std::vector<GtkFileFilter*> filters;
-  AddFilters(GTK_FILE_CHOOSER(dialog), params.accept_filters, true, &filters);
+  AddFilters(GTK_FILE_CHOOSER(dialog), params.accept_filters,
+             params.accept_extensions, params.accept_descriptions, true,
+             &filters);
 
   bool success = false;