Generate projects for Visual Studio 2017 by default

GN should generate projects for Visual Studio 2017 by default since this
is the default compiler now.

Bug: 683729
Change-Id: I560983cf4c228a785e0ed2648567c7e0f07584d4
Reviewed-on: https://chromium-review.googlesource.com/700258
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Reviewed-by: Bruce Dawson <brucedawson@chromium.org>
Commit-Queue: Tomasz Moniuszko <tmoniuszko@opera.com>
Cr-Original-Commit-Position: refs/heads/master@{#506665}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 7295a84e468138d53fc1f2259d737768f52e803c
diff --git a/tools/gn/command_gen.cc b/tools/gn/command_gen.cc
index ce3fa28..9c08a84 100644
--- a/tools/gn/command_gen.cc
+++ b/tools/gn/command_gen.cc
@@ -196,11 +196,11 @@
     return res;
   } else if (ide == kSwitchIdeValueVs || ide == kSwitchIdeValueVs2013 ||
              ide == kSwitchIdeValueVs2015 || ide == kSwitchIdeValueVs2017) {
-    VisualStudioWriter::Version version = VisualStudioWriter::Version::Vs2015;
+    VisualStudioWriter::Version version = VisualStudioWriter::Version::Vs2017;
     if (ide == kSwitchIdeValueVs2013)
       version = VisualStudioWriter::Version::Vs2013;
-    else if (ide == kSwitchIdeValueVs2017)
-      version = VisualStudioWriter::Version::Vs2017;
+    else if (ide == kSwitchIdeValueVs2015)
+      version = VisualStudioWriter::Version::Vs2015;
 
     std::string sln_name;
     if (command_line->HasSwitch(kSwitchSln))