Fix gn_all build on gcc 4.8

chrome/browser/media/webrtc/media_stream_devices_controller.h

Index: chrome/browser/media/webrtc/media_stream_devices_controller.h
diff --git a/chrome/browser/media/webrtc/media_stream_devices_controller.h b/chrome/browser/media/webrtc/media_stream_devices_controller.h
index 059ed42da9affc3096b32badc74c0940c6570ac0..edcaf40883dcacfab7dd75604116dd8871aa1e72 100644
--- a/chrome/browser/media/webrtc/media_stream_devices_controller.h
+++ b/chrome/browser/media/webrtc/media_stream_devices_controller.h
@@ -13,6 +13,7 @@
 #include "components/content_settings/core/common/content_settings.h"
 #include "content/public/browser/web_contents_delegate.h"
 
+class MediaStreamDevicesController;
 class Profile;
 class TabSpecificContentSettings;
 
@@ -32,6 +33,17 @@ namespace test {
 class MediaStreamDevicesControllerTestApi;
 }
 
+namespace internal {
+// Delegate showing permission prompts.

[sky, 2017/03/23 22:59:46]

Why does this need to move? What error happens with it in the private section of
the class?

[Tom (Use chromium acct), 2017/03/23 23:45:14]

Subclasses cannot derive from PermissionPromptDelegate (even if they are friend
classes) on gcc.

In file included from
../../chrome/browser/permissions/permission_request_manager_browsertest.cc:13:0:
../../chrome/browser/media/webrtc/media_stream_devices_controller.h:78:9: error:
'class MediaStreamDevicesController::PermissionPromptDelegate' is private
   class PermissionPromptDelegate {
         ^
../../chrome/browser/permissions/permission_request_manager_browsertest.cc:32:44:
error: within this context
     : public MediaStreamDevicesController::PermissionPromptDelegate {

+class PermissionPromptDelegate {
+ public:
+  virtual void ShowPrompt(
+      bool user_gesture,
+      content::WebContents* web_contents,
+      std::unique_ptr<MediaStreamDevicesController> controller) = 0;
+};
+}
+
 class MediaStreamDevicesController : public PermissionRequest {
  public:
   static void RequestPermissions(
@@ -74,15 +86,6 @@ class MediaStreamDevicesController : public PermissionRequest {
   friend class test::MediaStreamDevicesControllerTestApi;
   friend class policy::MediaStreamDevicesControllerBrowserTest;
 
-  // Delegate showing permission prompts.
-  class PermissionPromptDelegate {
-   public:
-    virtual void ShowPrompt(
-        bool user_gesture,
-        content::WebContents* web_contents,
-        std::unique_ptr<MediaStreamDevicesController> controller) = 0;
-  };
-
   class MediaPermissionStatus;
   class PermissionPromptDelegateImpl;
 
@@ -90,7 +93,7 @@ class MediaStreamDevicesController : public PermissionRequest {
       content::WebContents* web_contents,
       const content::MediaStreamRequest& request,
       const content::MediaResponseCallback& callback,
-      PermissionPromptDelegate* delegate);
+      internal::PermissionPromptDelegate* delegate);
 
   MediaStreamDevicesController(content::WebContents* web_contents,
                                const content::MediaStreamRequest& request,
@@ -165,7 +168,7 @@ class MediaStreamDevicesController : public PermissionRequest {
   // audio/video devices was granted or not.
   content::MediaResponseCallback callback_;
 
-  std::unique_ptr<PermissionPromptDelegate> delegate_;
+  std::unique_ptr<internal::PermissionPromptDelegate> delegate_;
 
   DISALLOW_COPY_AND_ASSIGN(MediaStreamDevicesController);
 };