Web MIDI: introduce WebMIDIClient API to request a permission

public/platform/WebMIDIAccessorClient.h

Index: public/platform/WebMIDIAccessorClient.h
diff --git a/public/platform/WebMIDIAccessorClient.h b/public/platform/WebMIDIAccessorClient.h
index a4a590d474f5542b74329067bd5fe53ba58ca2b1..9ab722c7a458c5def177f1529496e7c86fee5cb6 100644
--- a/public/platform/WebMIDIAccessorClient.h
+++ b/public/platform/WebMIDIAccessorClient.h
@@ -34,9 +34,12 @@
 #include "WebString.h"
 
 namespace WebKit {
+class WebSecurityOrigin;

[abarth-chromium, 2013/07/09 18:04:31]

This is a bad dependency.  You need to route the permission question "up" to the
public/web directory rather than "down" to the public/platform directory.  The
layering diagram looks like the following:

-- User Interface --
Code in Chromium
public/web
Code in Blink
public/platform
Code in Chromium
-- Operating System Services --

Permission questions are related to the user interface so they need to be routed
"up" the layering diagram.  Interfacing with MIDI devices is related to
operating system services, so they need to be routed "down" the layering
diagram.

 
 class WebMIDIAccessorClient {
 public:
+    virtual WebSecurityOrigin securityOrigin() const = 0;
+
     virtual void didAddInputPort(const WebString& id, const WebString& manufacturer, const WebString& name, const WebString& version) = 0;
     virtual void didAddOutputPort(const WebString& id, const WebString& manufacturer, const WebString& name, const WebString& version) = 0;