Use a mock WebAudioDevice for layout tests

content/shell/renderer/shell_content_renderer_client.cc

Index: content/shell/renderer/shell_content_renderer_client.cc
diff --git a/content/shell/renderer/shell_content_renderer_client.cc b/content/shell/renderer/shell_content_renderer_client.cc
index 68dccc99b926646175f32e7fc8108877060332da..a1522b9cab98e5107eb3398ac17ac42448a1d65e 100644
--- a/content/shell/renderer/shell_content_renderer_client.cc
+++ b/content/shell/renderer/shell_content_renderer_client.cc
@@ -25,6 +25,7 @@
 #include "webkit/mocks/mock_webhyphenator.h"
 #include "webkit/support/mock_webclipboard_impl.h"
 
+using WebKit::WebAudioDevice;
 using WebKit::WebClipboard;
 using WebKit::WebFrame;
 using WebKit::WebHyphenator;
@@ -153,6 +154,14 @@ ShellContentRendererClient::OverrideCreateMIDIAccessor(
   return interfaces->createMIDIAccessor(client);
 }
 
+WebAudioDevice*
+ShellContentRendererClient::OverrideCreateAudioDevice(
+    double sample_rate) {
+  WebTestInterfaces* interfaces =
+      ShellRenderProcessObserver::GetInstance()->test_interfaces();
+  return interfaces->createAudioDevice(sample_rate);
+}
+
 WebClipboard* ShellContentRendererClient::OverrideWebClipboard() {
   if (!CommandLine::ForCurrentProcess()->HasSwitch(switches::kDumpRenderTree))
     return NULL;