Browser-wide audio mirroring for TabCapture API

content/browser/renderer_host/media/web_contents_capture_util.cc

 // Copyright (c) 2012 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 "content/browser/renderer_host/media/web_contents_capture_util.h"
 
+#include "base/basictypes.h"
 #include "base/string_number_conversions.h"
 #include "base/string_piece.h"
+#include "base/string_util.h"
+
+namespace {
+
+const char kVirtualDeviceScheme[] = "virtual://";
+
+}  // namespace
 
 namespace content {
 
+std::string WebContentsCaptureUtil::AppendWebContentsDeviceScheme(
+    const std::string& device_id) {
+  return kVirtualDeviceScheme + device_id;
+}
+
+std::string WebContentsCaptureUtil::StripWebContentsDeviceScheme(
+    const std::string& device_id) {
+return (IsWebContentsDeviceId(device_id) ?
+            device_id.substr(arraysize(kVirtualDeviceScheme) - 1) :
+            device_id);
+}
+
+bool WebContentsCaptureUtil::IsWebContentsDeviceId(
+    const std::string& device_id) {
+  return StartsWithASCII(device_id, kVirtualDeviceScheme, true);
+}
+
 bool WebContentsCaptureUtil::ExtractTabCaptureTarget(
-    const std::string& device_id,
+    const std::string& device_id_param,
     int* render_process_id,
     int* render_view_id) {
+  DCHECK(IsWebContentsDeviceId(device_id_param));
+  const std::string device_id = device_id_param.substr(
+      arraysize(kVirtualDeviceScheme) - 1);
+
   const size_t sep_pos = device_id.find(':');
   if (sep_pos == std::string::npos)
     return false;
 
   const base::StringPiece component1(device_id.data(), sep_pos);
   const base::StringPiece component2(device_id.data() + sep_pos + 1,
                                      device_id.length() - sep_pos - 1);
 
   return (base::StringToInt(component1, render_process_id) &&
           base::StringToInt(component2, render_view_id));
 }
 
 }  // namespace content