Fix Visual Studio 2015 WebRtc x86 build.

webrtc/modules/audio_processing/transient/file_utils_unittest.cc

Index: webrtc/modules/audio_processing/transient/file_utils_unittest.cc
diff --git a/webrtc/modules/audio_processing/transient/file_utils_unittest.cc b/webrtc/modules/audio_processing/transient/file_utils_unittest.cc
index 7fb7d2d6a98feeec4cbc4436e4a5d30b33815f2c..b8d532f3a4f7230c005cac6d8e7f164469b90594 100644
--- a/webrtc/modules/audio_processing/transient/file_utils_unittest.cc
+++ b/webrtc/modules/audio_processing/transient/file_utils_unittest.cc
@@ -419,9 +419,9 @@ TEST_F(TransientFileUtilsTest, MAYBE_WriteFloatBufferToFile) {
   rtc::scoped_ptr<float[]> written_buffer(new float[kBufferLength]);
   rtc::scoped_ptr<float[]> read_buffer(new float[kBufferLength]);
 
-  written_buffer[0] = kPi;
-  written_buffer[1] = kE;
-  written_buffer[2] = kAvogadro;
+  written_buffer[0] = static_cast<float>(kPi);
+  written_buffer[1] = static_cast<float>(kE);
+  written_buffer[2] = static_cast<float>(kAvogadro);
 
   EXPECT_EQ(kBufferLength, WriteFloatBufferToFile(file.get(),
                                                   kBufferLength,