exo: extended-drag: Switch to const refs in delegate functions

R=oshima@chromium.org

Bug: 1099418
Change-Id: Ib3753a2dbc80995b69e4da6b0ef1221934f99310
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2511717
Auto-Submit: Nick Yamane <nickdiego@igalia.com>
Commit-Queue: Mitsuru Oshima <oshima@chromium.org>
Reviewed-by: Mitsuru Oshima <oshima@chromium.org>
Cr-Commit-Position: refs/heads/master@{#823331}

components/exo/extended_drag_source.h

@@ -42,8 +42,8 @@ class ExtendedDragSource : public DataSourceObserver,
    public:
     virtual bool ShouldAllowDropAnywhere() const = 0;
     virtual bool ShouldLockCursor() const = 0;
-    virtual void OnSwallowed(std::string mime_type) = 0;
-    virtual void OnUnswallowed(std::string mime_type,
+    virtual void OnSwallowed(const std::string& mime_type) = 0;
+    virtual void OnUnswallowed(const std::string& mime_type,
                                const gfx::Vector2d& offset) = 0;
     virtual void OnDataSourceDestroying() = 0;
 

components/exo/extended_drag_source_unittest.cc

@@ -77,12 +77,12 @@ class TestExtendedDragSourceDelegate : public ExtendedDragSource::Delegate {
 
   bool ShouldLockCursor() const override { return lock_cursor_; }
 
-  void OnSwallowed(std::string mime_type) override {
+  void OnSwallowed(const std::string& mime_type) override {
     ASSERT_FALSE(swallowed_);
     swallowed_ = true;
   }
 
-  void OnUnswallowed(std::string mime_type,
+  void OnUnswallowed(const std::string& mime_type,
                      const gfx::Vector2d& offset) override {
     ASSERT_TRUE(swallowed_);
     swallowed_ = false;

components/exo/wayland/zcr_extended_drag.cc

@@ -48,12 +48,12 @@ class ZcrExtendedDragSourceDelegate : public ExtendedDragSource::Delegate {
     return settings_ & ZCR_EXTENDED_DRAG_V1_OPTIONS_LOCK_CURSOR;
   }
 
-  void OnSwallowed(std::string mime_type) override {
+  void OnSwallowed(const std::string& mime_type) override {
     zcr_extended_drag_source_v1_send_swallow(resource_, mime_type.c_str());
     wl_client_flush(wl_resource_get_client(resource_));
   }
 
-  void OnUnswallowed(std::string mime_type,
+  void OnUnswallowed(const std::string& mime_type,
                      const gfx::Vector2d& offset) override {
     zcr_extended_drag_source_v1_send_unswallow(resource_, mime_type.c_str(),
                                                offset.x(), offset.y());