Add a console warning for rejected file-chooser dialog calls.

Bug: 936505
Change-Id: If468227536553d528951ce88744146c5f6913d58
Reviewed-on: https://chromium-review.googlesource.com/c/1495597
Commit-Queue: Mustaq Ahmed <mustaq@chromium.org>
Reviewed-by: Kent Tamura <tkent@chromium.org>
Cr-Commit-Position: refs/heads/master@{#636846}

third_party/blink/renderer/core/html/forms/file_input_type.cc

@@ -35,6 +35,7 @@
 #include "third_party/blink/renderer/core/html/forms/html_input_element.h"
 #include "third_party/blink/renderer/core/html_names.h"
 #include "third_party/blink/renderer/core/input_type_names.h"
+#include "third_party/blink/renderer/core/inspector/console_message.h"
 #include "third_party/blink/renderer/core/layout/layout_file_upload_control.h"
 #include "third_party/blink/renderer/core/page/chrome_client.h"
 #include "third_party/blink/renderer/core/page/drag_data.h"
@@ -157,14 +158,19 @@ void FileInputType::HandleDOMActivateEvent(Event& event) {
   if (GetElement().IsDisabledFormControl())
     return;
 
-  if (!LocalFrame::HasTransientUserActivation(
-          GetElement().GetDocument().GetFrame()))
+  HTMLInputElement& input = GetElement();
+  Document& document = input.GetDocument();
+
+  if (!LocalFrame::HasTransientUserActivation(document.GetFrame())) {
+    String message =
+        "File chooser dialog can only be shown with a user activation.";
+    document.AddConsoleMessage(ConsoleMessage::Create(
+        kJSMessageSource, kWarningMessageLevel, message));
     return;
+  }
 
   if (ChromeClient* chrome_client = GetChromeClient()) {
     FileChooserParams params;
-    HTMLInputElement& input = GetElement();
-    Document& document = input.GetDocument();
     bool is_directory = input.FastHasAttribute(kWebkitdirectoryAttr);
     if (is_directory)
       params.mode = FileChooserParams::Mode::kUploadFolder;

third_party/blink/web_tests/fast/forms/file/input-file-not-open-without-gesture-expected.txt

+CONSOLE WARNING: line 32: File chooser dialog can only be shown with a user activation.
 This file is to test that opening file dialog requires a user gesture. Please refer to https://bugs.webkit.org/show_bug.cgi?id=47593 for more details.
 Test opening file dialog without user gesture is PASSED