Update common_audio

Corresponds to upstream commit 524e9b043e7e86fd72353b987c9d5f6a1ebf83e1

Update notes:

 * Moved src/ to webrtc/ to easily diff against the third_party/webrtc
   in the chromium tree

 * ARM/NEON/MIPS support is not yet hooked up

 * Tests have not been copied

webrtc/system_wrappers/interface/cpu_features_wrapper.h

@@ -0,0 +1,51 @@
+/*
+ *  Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef WEBRTC_SYSTEM_WRAPPERS_INTERFACE_CPU_FEATURES_WRAPPER_H_
+#define WEBRTC_SYSTEM_WRAPPERS_INTERFACE_CPU_FEATURES_WRAPPER_H_
+
+#if defined(__cplusplus) || defined(c_plusplus)
+extern "C" {
+#endif
+
+#include "webrtc/typedefs.h"
+
+// List of features in x86.
+typedef enum {
+  kSSE2,
+  kSSE3
+} CPUFeature;
+
+// List of features in ARM.
+enum {
+  kCPUFeatureARMv7       = (1 << 0),
+  kCPUFeatureVFPv3       = (1 << 1),
+  kCPUFeatureNEON        = (1 << 2),
+  kCPUFeatureLDREXSTREX  = (1 << 3)
+};
+
+typedef int (*WebRtc_CPUInfo)(CPUFeature feature);
+
+// Returns true if the CPU supports the feature.
+extern WebRtc_CPUInfo WebRtc_GetCPUInfo;
+
+// No CPU feature is available => straight C path.
+extern WebRtc_CPUInfo WebRtc_GetCPUInfoNoASM;
+
+// Return the features in an ARM device.
+// It detects the features in the hardware platform, and returns supported
+// values in the above enum definition as a bitmask.
+extern uint64_t WebRtc_GetCPUFeaturesARM(void);
+
+#if defined(__cplusplus) || defined(c_plusplus)
+}  // extern "C"
+#endif
+
+#endif // WEBRTC_SYSTEM_WRAPPERS_INTERFACE_CPU_FEATURES_WRAPPER_H_