Plumb audio muting state to guest web-contents.

chrome/browser/apps/guest_view/web_view_browsertest.cc

Index: chrome/browser/apps/guest_view/web_view_browsertest.cc
diff --git a/chrome/browser/apps/guest_view/web_view_browsertest.cc b/chrome/browser/apps/guest_view/web_view_browsertest.cc
index 5a5819b8aae64eec1dd74d94c143052736d4eed2..8b5bdc2fa131991c2f2b470b5e712d2e179aece1 100644
--- a/chrome/browser/apps/guest_view/web_view_browsertest.cc
+++ b/chrome/browser/apps/guest_view/web_view_browsertest.cc
@@ -745,6 +745,70 @@ class WebViewDPITest : public WebViewTest {
   static float scale() { return 2.0f; }
 };
 
+class WebContentsAudioMutedObserver : public content::WebContentsObserver {
+ public:
+  WebContentsAudioMutedObserver(content::WebContents* web_contents,
+                                const base::Closure& muted_callback)
+      : WebContentsObserver(web_contents),
+        muted_callback_(muted_callback),
+        muting_update_observed_(false) {
+  }
+
+  // WebContentsObserver.
+  void DidUpdateAudioMutingState(bool muted) override {
+    muting_update_observed_ = true;
+    muted_callback_.Run();
+  }
+
+  bool muting_update_observed() { return muting_update_observed_; }
+
+ private:
+  base::Closure muted_callback_;
+  bool muting_update_observed_;
+
+  DISALLOW_COPY_AND_ASSIGN(WebContentsAudioMutedObserver);
+};
+
+IN_PROC_BROWSER_TEST_F(WebViewTest, AudioMutesWhileAttached) {
+  LoadAppWithGuest("web_view/simple");
+
+  content::WebContents* embedder = GetEmbedderWebContents();
+  content::WebContents* guest = GetGuestWebContents();
+
+  EXPECT_FALSE(embedder->IsAudioMuted());
+  EXPECT_FALSE(guest->IsAudioMuted());
+
+  embedder->SetAudioMuted(true);
+  EXPECT_TRUE(embedder->IsAudioMuted());
+  EXPECT_TRUE(guest->IsAudioMuted());
+
+  embedder->SetAudioMuted(false);
+  EXPECT_FALSE(embedder->IsAudioMuted());
+  EXPECT_FALSE(guest->IsAudioMuted());

[Charlie Reis, 2016/01/06 22:13:51]

Is it possible to mute a guest without muting the embedder?  Just wondering if
we should test what happens in that case (and if so, what happens if the
embedder is then muted and unmuted).

[wjmaclean, 2016/01/06 22:36:09]

At present there is no pathway to mute a guest directly, i.e. the only pathway
involves muting the embedder.

[Charlie Reis, 2016/01/07 00:11:02]

Acknowledged.

+}
+
+IN_PROC_BROWSER_TEST_F(WebViewTest, AudioMutesOnAttach) {
+  LoadAndLaunchPlatformApp("web_view/app_creates_webview",
+                           "WebViewTest.LAUNCHED");
+  content::WebContents* embedder = GetEmbedderWebContents();
+  embedder->SetAudioMuted(true);
+  EXPECT_TRUE(embedder->IsAudioMuted());
+
+  SendMessageToEmbedder("create-guest");
+  content::WebContents* guest =
+      GetGuestViewManager()->WaitForSingleGuestCreated();
+
+  EXPECT_TRUE(embedder->IsAudioMuted());
+  scoped_refptr<content::MessageLoopRunner> loop_runner(
+      new content::MessageLoopRunner);
+  WebContentsAudioMutedObserver observer(guest, loop_runner->QuitClosure());
+  // If the guest hasn't attached yet, it may not have received the muting
+  // update, in which case we should wait until it does.
+  if (!guest->IsAudioMuted() && !observer.muting_update_observed())

[Charlie Reis, 2016/01/06 22:13:51]

observer.muting_update_observed() can't be true here, can it?  We just created
the observer and it hasn't gotten a chance to observe anything.

[wjmaclean, 2016/01/06 22:36:09]

I suspect you're right, but I left the check in for safety. I can remove it if
you prefer.

+    loop_runner->Run();

[Charlie Reis, 2016/01/06 22:13:51]

nit: Most of the test observer classes I'm familiar with (e.g.,
TestNavigationObserver) keep the MessageLoopRunner internally and have a Wait
method to expose it.  Maybe that would be a bit cleaner here?

[wjmaclean, 2016/01/06 22:36:09]

Sure, I can do that.

+  EXPECT_TRUE(guest->IsAudioMuted());
+}
+
 // This test verifies that hiding the guest triggers WebContents::WasHidden().
 IN_PROC_BROWSER_TEST_F(WebViewVisibilityTest, GuestVisibilityChanged) {
   LoadAppWithGuest("web_view/visibility_changed");