Change default Windows compiler to VS 2015

build/vs_toolchain.py

Index: build/vs_toolchain.py
diff --git a/build/vs_toolchain.py b/build/vs_toolchain.py
index a944e9879cd361dd21f238886319ef2848d5d6b3..e02ec1f0b5c1fec46e824c79cc916c86270d5763 100755
--- a/build/vs_toolchain.py
+++ b/build/vs_toolchain.py
@@ -21,8 +21,8 @@ json_data_file = os.path.join(script_dir, 'win_toolchain.json')
 import gyp
 
 
-# Use MSVS2013 as the default toolchain.
-CURRENT_DEFAULT_TOOLCHAIN_VERSION = '2013'
+# Use MSVS2015 as the default toolchain.
+CURRENT_DEFAULT_TOOLCHAIN_VERSION = '2015'
 
 
 def SetEnvironmentAndGetRuntimeDllDirs():
@@ -274,7 +274,6 @@ def _GetDesiredVsToolchainHashes():
     # Update 1 with Debuggers, UCRT installers and ucrtbased.dll
     return ['5a85cf1ce842f7cc96b9d17039a445a9dc9cf0dd']
   else:
-    # Default to VS2013.
     return ['9ff97c632ae1fee0c98bcd53e71770eb3a0d8deb']
 
 
@@ -308,6 +307,9 @@ def Update(force=False):
         depot_tools_win_toolchain):
     import find_depot_tools
     depot_tools_path = find_depot_tools.add_depot_tools_to_path()
+    # Necessary so that get_toolchain_if_necessary.py will put the VS toolkit
+    # in the correct directory.
+    os.environ['GYP_MSVS_VERSION'] = GetVisualStudioVersion()
     get_toolchain_args = [
         sys.executable,
         os.path.join(depot_tools_path,