base: Fix warnings found by clang chromium-style plugin on Windows.

http://build.chromium.org/p/chromium.fyi/builders/CrWinClang/builds/596/steps/compile/logs/stdio

..\..\base/win/shortcut.h(51,3) :  warning(clang): [chromium-style] Complex constructor has an inlined body.
ShortcutProperties() : icon_index(-1), dual_mode(false), options(0U) {}
                      ^
..\..\base/win/shortcut.h(32,1) :  warning(clang): [chromium-style] Complex class/struct needs an explicit out-of-line destructor.
struct ShortcutProperties {
    ^
2 warnings generated.

BUG=467287
R=thakis@chromium.org

Review URL: https://codereview.chromium.org/1100403003

Cr-Commit-Position: refs/heads/master@{#326995}

base/win/shortcut.cc

@@ -42,6 +42,13 @@ void InitializeShortcutInterfaces(
 
 }  // namespace
 
+ShortcutProperties::ShortcutProperties()
+    : icon_index(-1), dual_mode(false), options(0U) {
+}
+
+ShortcutProperties::~ShortcutProperties() {
+}
+
 bool CreateOrUpdateShortcutLink(const FilePath& shortcut_path,
                                 const ShortcutProperties& properties,
                                 ShortcutOperation operation) {

base/win/shortcut.h

@@ -7,6 +7,7 @@
 
 #include <windows.h>
 
+#include "base/base_export.h"
 #include "base/files/file_path.h"
 #include "base/logging.h"
 #include "base/strings/string16.h"
@@ -29,7 +30,7 @@ enum ShortcutOperation {
 // creation/update, others will be ignored.
 // Callers are encouraged to use the setters provided which take care of
 // setting |options| as desired.
-struct ShortcutProperties {
+struct BASE_EXPORT ShortcutProperties {
   enum IndividualProperties {
     PROPERTIES_TARGET = 1U << 0,
     PROPERTIES_WORKING_DIR = 1U << 1,
@@ -48,7 +49,8 @@ struct ShortcutProperties {
     PROPERTIES_ALL = PROPERTIES_BASIC | PROPERTIES_WIN7
   };
 
-  ShortcutProperties() : icon_index(-1), dual_mode(false), options(0U) {}
+  ShortcutProperties();
+  ~ShortcutProperties();
 
   void set_target(const FilePath& target_in) {
     target = target_in;