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

chrome/browser/extensions/api/tab_capture/offscreen_presentation.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/extensions/api/tab_capture/offscreen_presentation.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "chrome/browser/extensions/api/tab_capture/tab_capture_registry.h"
+#include "chrome/browser/media/router/one_ua_presentation_router.h"
+#include "chrome/browser/media/router/one_ua_presentation_router_factory.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/web_contents_sizer.h"
+#include "content/public/browser/render_frame_host.h"
+#include "content/public/browser/render_process_host.h"
 #include "content/public/browser/render_widget_host_view.h"
 #include "content/public/browser/web_contents.h"
 #include "extensions/browser/extension_host.h"
 #include "extensions/browser/process_manager.h"
 
 #if defined(USE_AURA)
 #include "base/memory/weak_ptr.h"
 #include "base/thread_task_runner_handle.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/browser_list.h"
@@ skipping 153 matching lines @@
   }
   return nullptr;
 }
 
 OffscreenPresentation::OffscreenPresentation(OffscreenPresentationsOwner* owner,
                                              const GURL& start_url,
                                              const std::string& id)
     : owner_(owner),
       start_url_(start_url),
       presentation_id_(id),
-      profile_(Profile::FromBrowserContext(
-                   owner->extension_web_contents()->GetBrowserContext())
-               ->CreateOffTheRecordProfile()),
+      profile_(Profile::FromBrowserContext(owner->extension_web_contents()
+                                               ->GetBrowserContext())
+                   ->CreateOffTheRecordProfile()),
+      one_ua_presentation_router_(

[miu, 2015/09/17 00:09:20]

IMO, you should not store a pointer to the router in this class.  It is only
used once at start-up, and once at destruction time to register/deregister.

Incorporating mfoltz's comment below, the register call would look like:

  media_router::OneUAPresentationRouterFactory::
      GetOrCreateForBrowserContext(owner_->extension_web_contents()
                                       ->GetBrowserContext())
          ->RegisterPresenter(presentation_id(),
                              presentation_web_contents_.get());

[imcheng, 2015/09/26 01:21:56]

Done.

+          media_router::OneUAPresentationRouterFactory::
+              GetOrCreateForBrowserContext(owner_->extension_web_contents()
+                                               ->GetBrowserContext())),
       capture_poll_timer_(false, false),
       content_capture_was_detected_(false) {
   DCHECK(profile_);
+  DCHECK(one_ua_presentation_router_);
 }
 
 OffscreenPresentation::~OffscreenPresentation() {
   DVLOG(1) << "Destroying OffscreenPresentation for start_url="
            << start_url_.spec();
 }
 
 void OffscreenPresentation::Start(const gfx::Size& initial_size) {
   DCHECK(start_time_.is_null());
   DVLOG(1) << "Starting OffscreenPresentation with initial size of "
@@ skipping 16 matching lines @@
   // Mute audio output.  When tab capture starts, the audio will be
   // automatically unmuted, but will be captured into the MediaStream.
   presentation_web_contents_->SetAudioMuted(true);
 
   // Navigate to the initial URL of the presentation.
   content::NavigationController::LoadURLParams load_params(start_url_);
   load_params.should_replace_current_entry = true;
   load_params.should_clear_history_list = true;
   presentation_web_contents_->GetController().LoadURLWithParams(load_params);
 
+  // If the offscreen tab is for a 1-UA presentation, register the tab's main
+  // frame as a presenter frame in OneUAPresentationRouter.
+  // Use the OneUAPresentationRouter keyed off the owner's BrowserContext.
+  // We assume that the presentation's potential controllers will be using the
+  // same OneUAPresentationRouter instance to connect with the presenter.
+  content::RenderFrameHost* render_frame_host =
+      presentation_web_contents_->GetMainFrame();
+  DCHECK(render_frame_host);
+  std::pair<int, int> rfh_id(render_frame_host->GetProcess()->GetID(),
+                             render_frame_host->GetRoutingID());
+
+  one_ua_presentation_router_->RegisterPresenter(presentation_id(), rfh_id);

[mark a. foltz, 2015/09/11 23:24:20]

Can RegisterPresenter() just take the (id, WebContents) and do the lookups
internally?

[miu, 2015/09/17 00:09:20]

+1 to mfoltz's comment.

Also, is registering the presentation here the correct order-of-operations? 
Meaning, it seems like the presentation should be registered *before* the
navigation is started (on L231-235 above).

[imcheng, 2015/09/26 01:21:56]

Ok, looks like main frame should be initialized when WebContents is created, so
I don't have to wait for LoadURLWithParams.

Is LoadURLWithParams async though? i.e., any presentation api requests from the
offscreen tab won't reach the browser process until after this extension
function returns.

Anyhow, I changed it to call RegisterPresenter before LoadURLWithParams is
called.

[imcheng, 2015/09/26 01:21:56]

Done.

[miu, 2015/09/27 00:22:08]

Probably not, but there are multiple processes and threads involved.  Might as
well pretend the worst-case raciness is possible (even if it totally is not) and
just move the lines of code up a bit.  It'll also help make this code more
robust against future changes that could introduce raciness.

[imcheng, 2015/09/30 01:13:41]

Acknowledged. Now I call
ReceiverPresentationServiceDelegate::CreateForWebContents (which calls
RegisterReceiverTab) before navigation.

+
   start_time_ = base::TimeTicks::Now();
   DieIfContentCaptureEnded();
 }
 
 void OffscreenPresentation::CloseContents(WebContents* source) {
   DCHECK_EQ(presentation_web_contents_.get(), source);
   // Javascript in the page called window.close().
   DVLOG(1) << "OffscreenPresentation will die at renderer's request for "
               "start_url=" << start_url_.spec();
-  owner_->ClosePresentation(this);
+  Close();
 }
 
 bool OffscreenPresentation::ShouldSuppressDialogs(WebContents* source) {
   DCHECK_EQ(presentation_web_contents_.get(), source);
   // Suppress all because there is no possible direct user interaction with
   // dialogs.
   return true;
 }
 
 bool OffscreenPresentation::ShouldFocusLocationBarByDefault(
@@ skipping 189 matching lines @@
     current_fs_view->SetSize(presentation_web_contents_->GetPreferredSize());
 }
 
 void OffscreenPresentation::DieIfContentCaptureEnded() {
   DCHECK(presentation_web_contents_.get());
 
   if (content_capture_was_detected_) {
     if (presentation_web_contents_->GetCapturerCount() == 0) {
       DVLOG(2) << "Capture of OffscreenPresentation content has stopped for "
                   "start_url=" << start_url_.spec();
-      owner_->ClosePresentation(this);
+      Close();
       return;
     } else {
       DVLOG(3) << "Capture of OffscreenPresentation content continues for "
                   "start_url=" << start_url_.spec();
     }
   } else if (presentation_web_contents_->GetCapturerCount() > 0) {
     DVLOG(2) << "Capture of OffscreenPresentation content has started for "
                 "start_url=" << start_url_.spec();
     content_capture_was_detected_ = true;
   } else if (base::TimeTicks::Now() - start_time_ >
                  base::TimeDelta::FromSeconds(kMaxSecondsToWaitForCapture)) {
     // More than a minute has elapsed since this OffscreenPresentation was
     // started and content capture still hasn't started.  As a safety
     // precaution, assume that content capture is never going to start and die
     // to free up resources.
     LOG(WARNING) << "Capture of OffscreenPresentation content did not start "
                     "within timeout for start_url=" << start_url_.spec();
-    owner_->ClosePresentation(this);
+    Close();
     return;
   }
 
   // Schedule the timer to check again in a second.
   capture_poll_timer_.Start(
       FROM_HERE,
       base::TimeDelta::FromSeconds(kPollIntervalInSeconds),
       base::Bind(&OffscreenPresentation::DieIfContentCaptureEnded,
                  base::Unretained(this)));
 }
 
+void OffscreenPresentation::Close() {
+  content::RenderFrameHost* render_frame_host =
+      presentation_web_contents_->GetMainFrame();
+  DCHECK(render_frame_host);
+  std::pair<int, int> rfh_id(render_frame_host->GetProcess()->GetID(),
+                             render_frame_host->GetRoutingID());
+  one_ua_presentation_router_->UnregisterPresenter(rfh_id);

[mark a. foltz, 2015/09/11 23:24:20]

UnregisterPresentation(WebContents*)

[imcheng, 2015/09/26 01:21:56]

Done.

+  owner_->ClosePresentation(this);
+}
+
 }  // namespace extensions