[Presentation API] 1-UA presentation support + presenter APIs.

chrome/browser/chrome_content_browser_client.cc

Index: chrome/browser/chrome_content_browser_client.cc
diff --git a/chrome/browser/chrome_content_browser_client.cc b/chrome/browser/chrome_content_browser_client.cc
index 71adb8355ef636cdc07f1de89521c80a5813a689..608551ef89c0ad75deedcde68241f89b603d789d 100644
--- a/chrome/browser/chrome_content_browser_client.cc
+++ b/chrome/browser/chrome_content_browser_client.cc
@@ -265,6 +265,7 @@
 
 #if defined(ENABLE_MEDIA_ROUTER)
 #include "chrome/browser/media/router/presentation_service_delegate_impl.h"
+#include "chrome/browser/media/router/receiver_presentation_service_delegate_impl.h"
 #endif
 
 using base::FileDescriptor;
@@ -2594,10 +2595,14 @@ content::PresentationServiceDelegate*
 ChromeContentBrowserClient::GetPresentationServiceDelegate(
       content::WebContents* web_contents) {
 #if defined(ENABLE_MEDIA_ROUTER)
-  if (switches::MediaRouterEnabled() &&
-      !web_contents->GetBrowserContext()->IsOffTheRecord()) {
-    return media_router::PresentationServiceDelegateImpl::
-        GetOrCreateForWebContents(web_contents);
+  if (switches::MediaRouterEnabled()) {
+    if (web_contents->GetBrowserContext()->IsOffTheRecord()) {
+      return media_router::ReceiverPresentationServiceDelegateImpl::

[miu, 2015/10/07 21:51:46]

This is a little confusing.  How is ReceiverPresentationServiceDelegateImpl
appropriate for all off-the-record profiles?  Doesn't it only pertain to
off-screen tabs?

Perhaps this code should be:

  if (auto* impl = ReceiverPresServiceDelegateImpl::FromWebContents(...))
    return impl;  // WebContents is an off-screen tab.
  return PresentationServiceDelegateImpl::GetOrCreateForWebContents(...);

Also, OOC, should we be worried about extension background pages attempting to
use the navigator.presentation API directly?  Do we want to allow or forbid
that?

[imcheng, 2015/10/10 04:39:43]

We've disabled presentation API in incognito mode, so this method should return
null for non-offscreen incognito WebContents. I will restructure this and add
some comments so it's clearer.

+          FromWebContents(web_contents);
+    } else {
+      return media_router::PresentationServiceDelegateImpl::
+          GetOrCreateForWebContents(web_contents);
+    }
   }
 #endif
   return nullptr;