Implement ui::ClipboardMus.

ui/base/clipboard/clipboard.h

Index: ui/base/clipboard/clipboard.h
diff --git a/ui/base/clipboard/clipboard.h b/ui/base/clipboard/clipboard.h
index 40af4df4f2fe2d1568227ee242f4118648c67d53..3a9d30bb136ded54d10926420ff2203c552c7fbe 100644
--- a/ui/base/clipboard/clipboard.h
+++ b/ui/base/clipboard/clipboard.h
@@ -9,6 +9,7 @@
 #include <stdint.h>
 
 #include <map>
+#include <memory>
 #include <string>
 #include <vector>
 
@@ -60,9 +61,13 @@ class UI_BASE_EXPORT Clipboard : NON_EXPORTED_BASE(public base::ThreadChecker) {
   static const char kMimeTypeText[];
   static const char kMimeTypeURIList[];
   static const char kMimeTypeDownloadURL[];
+  static const char kMimeTypeMozillaURL[];
   static const char kMimeTypeHTML[];
   static const char kMimeTypeRTF[];
   static const char kMimeTypePNG[];
+  static const char kMimeTypeWebCustomData[];
+  static const char kMimeTypeWebkitSmartPaste[];
+  static const char kMimeTypePepperCustomData[];
 
   // Platform neutral holder for native data representation of a clipboard type.
   struct UI_BASE_EXPORT FormatType {
@@ -137,6 +142,14 @@ class UI_BASE_EXPORT Clipboard : NON_EXPORTED_BASE(public base::ThreadChecker) {
   static void SetAllowedThreads(
       const std::vector<base::PlatformThreadId>& allowed_threads);
 
+  // Sets the clipboard for the current thread. Previously, there was only
+  // one clipboard implementation on a platform; now that mus exists, during
+  // mus app startup, we need to specifically initialize mus instead of the
+  // current platform clipboard. We take ownership of |platform_clipboard|. (We
+  // can't use unique_ptr since we don't want to expose the destructor.)

[dcheng, 2016/06/04 06:14:00]

Is the last part of this comment still accurate?

[Elliot Glaysher, 2016/06/06 20:10:12]

Done.

+  static void SetClipboardForCurrentThread(
+      std::unique_ptr<Clipboard> platform_clipboard);
+
   // Returns the clipboard object for the current thread.
   //
   // Most implementations will have at most one clipboard which will live on
@@ -310,6 +323,10 @@ class UI_BASE_EXPORT Clipboard : NON_EXPORTED_BASE(public base::ThreadChecker) {
   // For access to WriteObjects().
   friend class ScopedClipboardWriter;
   friend class TestClipboard;
+  // For SetClipboardForCurrentThread's argument.
+  friend struct std::default_delete<Clipboard>;
+
+  static base::PlatformThreadId GetAndValidateThreadID();
 
   // A list of allowed threads. By default, this is empty and no thread checking
   // is done (in the unit test case), but a user (like content) can set which