Mouse lock implementation, including the renderer side and the Windows version of the browser side.

content/browser/renderer_host/render_widget_host_view.h

Index: content/browser/renderer_host/render_widget_host_view.h
diff --git a/content/browser/renderer_host/render_widget_host_view.h b/content/browser/renderer_host/render_widget_host_view.h
index 3a85148269972308b921184627769a8c7ee2e3aa..79de6838ac5d8b768ac94731cfe1b5224e48126e 100644
--- a/content/browser/renderer_host/render_widget_host_view.h
+++ b/content/browser/renderer_host/render_widget_host_view.h
@@ -329,9 +329,15 @@ class RenderWidgetHostView {
     reserved_rect_ = reserved_rect;
   }
 
+  virtual bool LockMouse();
+  virtual void UnlockMouse();
+
+  bool mouse_locked() const { return mouse_locked_; }
+
  protected:
   // Interface class only, do not construct.
-  RenderWidgetHostView() : popup_type_(WebKit::WebPopupTypeNone) {}
+  RenderWidgetHostView() : popup_type_(WebKit::WebPopupTypeNone),
+                           mouse_locked_(false) {}
 
   // Whether this view is a popup and what kind of popup it is (select,
   // autofill...).
@@ -345,6 +351,13 @@ class RenderWidgetHostView {
   // rendered to draw the resize corner, sidebar mini tabs etc.
   gfx::Rect reserved_rect_;
 
+  // While the mouse is locked, the cursor is hidden from the user. Mouse events
+  // are still generated. However, the position they report is the last known
+  // mouse position just as mouse lock was entered; the movement they report
+  // indicates what the change in position of the mouse would be had it not been
+  // locked.
+  bool mouse_locked_;
+
  private:
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostView);
 };