serial: Hide help button until help center link ready

This change hides the help button in the serial port chooser dialog
since the help center page it would automatically navigate to is not yet
available.

Bug: 1085149
Change-Id: I00e2d6523e2a64a28e78675186327afe990fc7a0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2619001
Auto-Submit: Reilly Grant <reillyg@chromium.org>
Commit-Queue: Joshua Bell <jsbell@chromium.org>
Reviewed-by: Joshua Bell <jsbell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#843331}

chrome/browser/ui/serial/serial_chooser_controller.cc

@@ -49,6 +49,10 @@ SerialChooserController::~SerialChooserController() {
     RunCallback(/*port=*/nullptr);
 }
 
+bool SerialChooserController::ShouldShowHelpButton() const {
+  return false;
+}
+
 base::string16 SerialChooserController::GetNoOptionsText() const {
   return l10n_util::GetStringUTF16(IDS_DEVICE_CHOOSER_NO_DEVICES_FOUND_PROMPT);
 }

chrome/browser/ui/serial/serial_chooser_controller.h

@@ -35,6 +35,7 @@ class SerialChooserController final
   ~SerialChooserController() override;
 
   // ChooserController:
+  bool ShouldShowHelpButton() const override;
   base::string16 GetNoOptionsText() const override;
   base::string16 GetOkButtonLabel() const override;
   std::pair<base::string16, base::string16> GetThrobberLabelAndTooltip()