media: Add MediaPermission interface and MediaPermissionDispatcher.

media/blink/webencryptedmediaclient_impl.cc

Index: media/blink/webencryptedmediaclient_impl.cc
diff --git a/media/blink/webencryptedmediaclient_impl.cc b/media/blink/webencryptedmediaclient_impl.cc
index dd1eaaca851e7a86b5fb319d2c2f9bd26c144534..ced99e076d75e32cc248f0ee4ed7cb2d31a805cc 100644
--- a/media/blink/webencryptedmediaclient_impl.cc
+++ b/media/blink/webencryptedmediaclient_impl.cc
@@ -8,6 +8,7 @@
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "media/base/key_systems.h"
+#include "media/base/media_permission.h"
 #include "net/base/mime_util.h"
 #include "third_party/WebKit/public/platform/WebEncryptedMediaRequest.h"
 #include "third_party/WebKit/public/platform/WebMediaKeySystemConfiguration.h"
@@ -131,8 +132,12 @@ static bool GetSupportedConfiguration(
 }
 
 WebEncryptedMediaClientImpl::WebEncryptedMediaClientImpl(
-    scoped_ptr<CdmFactory> cdm_factory)
-    : cdm_factory_(cdm_factory.Pass()) {
+    scoped_ptr<CdmFactory> cdm_factory,
+    MediaPermission* media_permission)
+    : cdm_factory_(cdm_factory.Pass()), media_permission_(media_permission) {
+  if (!media_permission_) {

[xhwang, 2015/01/26 21:49:06]

Need this to suppress a unused memeber variable warning/error on
|media_mermission_|.

FYI, |media_permission| could be null. See the change in html_document.cc.

[ddorwin, 2015/01/26 23:33:46]

Why not just an unused parameter macro? Or do you really want the logging?
Either way, the macro (with DVLOG_IF) would probably be better.
Are we going to need to check for null before calling? Should html_document.cc
provide a dummy impl instead?

[xhwang, 2015/01/27 00:01:58]

I remember we had that macro before, but I can't find it now.
DVLOG_IF doesn't work because it doesn't check the condition is release builds.
I debated about that. Allowing null seems to be simpler. 

Also, there's no permission code hooked up in HtmlViewer yet. So the dummy impl
would pretty much be NOTIMPLEMENTED() and I am not sure whether it should return
true or false. Currently HTMLViewer only supports clear key, so we actually
don't need permission check for now. How about revisiting this later when we add
more key system support and hook up permission service with HTMLViewer?

[ddorwin, 2015/01/27 00:09:03]

Perhaps we just remove parameters (this is a member) in that case. However, when
we need a parameter for a DCHECK, we apparently automatically handle the opt
build case:
https://code.google.com/p/chromium/codesearch#chromium/src/base/logging.h&q=u....
That may not apply to DLOG is not, though.
Ack

[xhwang, 2015/01/27 00:34:05]

Done.

However, when

+    DVLOG(2) << "Null |media_permission_|.";
+  }

[ddorwin, 2015/01/26 23:33:46]

TODO: Do something with the new pointer?

[xhwang, 2015/01/27 00:01:58]

Done.

 }
 
 WebEncryptedMediaClientImpl::~WebEncryptedMediaClientImpl() {