Support for defered media load to cast_content_render_client.

Adds cast_media_load_dererrer to prevent unwanted media from being
played in web_contents that are not currently visible.

R=gunsch@chromium.org
BUG=

Review URL: https://codereview.chromium.org/824733002

Cr-Commit-Position: refs/heads/master@{#309471}

5 files changed, 79 insertions, 0 deletions

diff --git a/chromecast/chromecast.gyp b/chromecast/chromecast.gyp
index cf7ed71..b8595ba 100644
--- a/chromecast/chromecast.gyp
+++ b/chromecast/chromecast.gyp
@@ -174,6 +174,8 @@
         'common/pref_names.h',
         'renderer/cast_content_renderer_client.cc',
         'renderer/cast_content_renderer_client.h',
+        'renderer/cast_media_load_deferrer.cc',
+        'renderer/cast_media_load_deferrer.h',
         'renderer/key_systems_cast.cc',
         'renderer/key_systems_cast.h',
       ],
diff --git a/chromecast/renderer/cast_content_renderer_client.cc b/chromecast/renderer/cast_content_renderer_client.cc
index c2d91de..a01ea77 100644
--- a/chromecast/renderer/cast_content_renderer_client.cc
+++ b/chromecast/renderer/cast_content_renderer_client.cc
@@ -9,6 +9,7 @@
 #include "base/command_line.h"
 #include "base/memory/memory_pressure_listener.h"
 #include "chromecast/common/chromecast_switches.h"
+#include "chromecast/renderer/cast_media_load_deferrer.h"
 #include "chromecast/renderer/key_systems_cast.h"
 #include "chromecast/renderer/media/cma_media_renderer_factory.h"
 #include "components/dns_prefetch/renderer/prescient_networking_dispatcher.h"
@@ -89,5 +90,17 @@ CastContentRendererClient::GetPrescientNetworking() {
   return prescient_networking_dispatcher_.get();
 }
 
+void CastContentRendererClient::DeferMediaLoad(
+    content::RenderFrame* render_frame,
+    const base::Closure& closure) {
+  if (!render_frame->IsHidden()) {
+    closure.Run();
+    return;
+  }
+
+  // Lifetime is tied to |render_frame| via content::RenderFrameObserver.
+  new CastMediaLoadDeferrer(render_frame, closure);
+}
+
 }  // namespace shell
 }  // namespace chromecast
diff --git a/chromecast/renderer/cast_content_renderer_client.h b/chromecast/renderer/cast_content_renderer_client.h
index 7b60e6e..67c4529 100644
--- a/chromecast/renderer/cast_content_renderer_client.h
+++ b/chromecast/renderer/cast_content_renderer_client.h
@@ -30,6 +30,8 @@ class CastContentRendererClient : public content::ContentRendererClient {
   scoped_ptr<media::RendererFactory> CreateMediaRendererFactory(
       content::RenderFrame* render_frame) override;
   blink::WebPrescientNetworking* GetPrescientNetworking() override;
+  void DeferMediaLoad(content::RenderFrame* render_frame,
+                      const base::Closure& closure) override;
 
  private:
   scoped_ptr<dns_prefetch::PrescientNetworkingDispatcher>
diff --git a/chromecast/renderer/cast_media_load_deferrer.cc b/chromecast/renderer/cast_media_load_deferrer.cc
new file mode 100644
index 0000000..0f84657
--- /dev/null
+++ b/chromecast/renderer/cast_media_load_deferrer.cc
@@ -0,0 +1,27 @@
+// Copyright 2014 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 "chromecast/renderer/cast_media_load_deferrer.h"
+
+#include "base/callback_helpers.h"
+#include "base/logging.h"
+
+namespace chromecast {
+
+CastMediaLoadDeferrer::CastMediaLoadDeferrer(
+    content::RenderFrame* render_frame,
+    const base::Closure& continue_loading_cb)
+    : content::RenderFrameObserver(render_frame),
+      continue_loading_cb_(continue_loading_cb) {
+  DCHECK(!continue_loading_cb_.is_null());
+}
+
+CastMediaLoadDeferrer::~CastMediaLoadDeferrer() {}
+
+void CastMediaLoadDeferrer::WasShown() {
+  continue_loading_cb_.Run();
+  delete this;
+}
+
+}  // namespace chromecast
diff --git a/chromecast/renderer/cast_media_load_deferrer.h b/chromecast/renderer/cast_media_load_deferrer.h
new file mode 100644
index 0000000..72a57ca
--- /dev/null
+++ b/chromecast/renderer/cast_media_load_deferrer.h
@@ -0,0 +1,35 @@
+// Copyright 2014 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.
+
+#ifndef CHROMECAST_RENDERER_CAST_MEDIA_LOAD_DEFERRER_H_
+#define CHROMECAST_RENDERER_CAST_MEDIA_LOAD_DEFERRER_H_
+
+#include "base/callback.h"
+#include "base/macros.h"
+#include "content/public/renderer/render_frame_observer.h"
+
+namespace chromecast {
+
+// Defers media player loading in background web apps until brought into
+// foreground.
+class CastMediaLoadDeferrer : public content::RenderFrameObserver {
+ public:
+  // Will run |closure| to continue loading the media resource once the page is
+  // swapped in.
+  CastMediaLoadDeferrer(content::RenderFrame* render_frame,
+                        const base::Closure& continue_loading_cb);
+  ~CastMediaLoadDeferrer() override;
+
+ private:
+  // content::RenderFrameObserver implementation:
+  void WasShown() override;
+
+  base::Closure continue_loading_cb_;
+
+  DISALLOW_COPY_AND_ASSIGN(CastMediaLoadDeferrer);
+};
+
+}  // namespace chromecast
+
+#endif  // CHROMECAST_RENDERER_CAST_MEDIA_LOAD_DEFERRER_H_