Rewrite std::string("") to std::string(), Linux edition.

ppapi/shared_impl/ppb_audio_shared.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 "ppapi/shared_impl/ppb_audio_shared.h"
 
 #include "base/logging.h"
 #include "media/audio/shared_memory_util.h"
 #include "ppapi/shared_impl/ppapi_globals.h"
 
@@ skipping 62 matching lines @@
     base::SharedMemoryHandle shared_memory_handle,
     size_t shared_memory_size,
     base::SyncSocket::Handle socket_handle,
     int sample_frame_count) {
   socket_.reset(new base::CancelableSyncSocket(socket_handle));
   shared_memory_.reset(new base::SharedMemory(shared_memory_handle, false));
   shared_memory_size_ = shared_memory_size;
 
   if (!shared_memory_->Map(
           media::TotalSharedMemorySizeInBytes(shared_memory_size_))) {
-    PpapiGlobals::Get()->LogWithSource(instance, PP_LOGLEVEL_WARNING, "",
-      "Failed to map shared memory for PPB_Audio_Shared.");
+    PpapiGlobals::Get()->LogWithSource(
+        instance,
+        PP_LOGLEVEL_WARNING,
+        std::string(),
+        "Failed to map shared memory for PPB_Audio_Shared.");
   } else {
     audio_bus_ = media::AudioBus::WrapMemory(
         kChannels, sample_frame_count, shared_memory_->memory());
     // Setup integer audio buffer for user audio data.
     client_buffer_size_bytes_ =
         audio_bus_->frames() * audio_bus_->channels() * kBytesPerSample;
     client_buffer_.reset(new uint8_t[client_buffer_size_bytes_]);
   }
 
   StartThread();
@@ skipping 77 matching lines @@
     // padding for alignment, there may be more data available than this.  We're
     // relying on AudioSyncReader::Read() to parse this with that in mind.
     // Rename these methods to Set/GetActualFrameCount().
     media::SetActualDataSizeInBytes(
         shared_memory_.get(), shared_memory_size_,
         audio_bus_->frames() * bytes_per_frame);
   }
 }
 
 }  // namespace ppapi