Make keyboard shortcuts work on Mac

When the renderer doesn't handle a key event, we pass it off to the main menu
to see if it can handle it.

Part of #2.

brightray/brightray.gyp

@@ -23,6 +23,9 @@
         'browser/browser_main_parts.cc',
         'browser/browser_main_parts.h',
         'browser/browser_main_parts_mac.mm',
+        'browser/default_web_contents_delegate.cc',
+        'browser/default_web_contents_delegate.h',
+        'browser/default_web_contents_delegate_mac.mm',
         'browser/devtools_delegate.cc',
         'browser/devtools_delegate.h',
         'browser/devtools_frontend.cc',

brightray/browser/default_web_contents_delegate.cc

@@ -0,0 +1,11 @@
+#include "browser/default_web_contents_delegate.h"
+
+namespace brightray {
+
+DefaultWebContentsDelegate::DefaultWebContentsDelegate() {
+}
+
+DefaultWebContentsDelegate::~DefaultWebContentsDelegate() {
+}
+
+}

brightray/browser/default_web_contents_delegate.h

@@ -0,0 +1,21 @@
+#ifndef BRIGHTRAY_BROWSER_DEFAULT_WEB_CONTENTS_DELEGATE_H_
+#define BRIGHTRAY_BROWSER_DEFAULT_WEB_CONTENTS_DELEGATE_H_
+
+#include "content/public/browser/web_contents_delegate.h"
+
+namespace brightray {
+
+// This class provides some sane default behaviors to any content::WebContents instance (e.g.,
+// keyboard shortcut handling on Mac).
+class DefaultWebContentsDelegate : public content::WebContentsDelegate {
+public:
+  DefaultWebContentsDelegate();
+  ~DefaultWebContentsDelegate();
+
+protected:
+  virtual void HandleKeyboardEvent(content::WebContents*, const content::NativeWebKeyboardEvent&) OVERRIDE;
+};
+
+}
+
+#endif

brightray/browser/default_web_contents_delegate_mac.mm

@@ -0,0 +1,15 @@
+#import "browser/default_web_contents_delegate.h"
+
+#import "content/public/browser/native_web_keyboard_event.h"
+#import <AppKit/AppKit.h>
+
+namespace brightray {
+
+void DefaultWebContentsDelegate::HandleKeyboardEvent(content::WebContents*, const content::NativeWebKeyboardEvent& event) {
+  if (event.skip_in_browser)
+    return;
+
+  [[NSApp mainMenu] performKeyEquivalent:event.os_event];
+}
+
+}