[CRD iOS] Preserve viewport state when toggling the soft keyboard

remoting/client/ui/desktop_viewport.h

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef REMOTING_CLIENT_UI_DESKTOP_VIEWPORT_H_
 #define REMOTING_CLIENT_UI_DESKTOP_VIEWPORT_H_
 
 #include "base/callback.h"
 #include "remoting/client/ui/view_matrix.h"
 
@@ skipping 17 matching lines @@
 // You may either manipulate the desktop on the surface coordinate or manipulate
 // the viewport on the desktop coordinate, depending on your choice of the
 // reference frame.
 class DesktopViewport {
  public:
   using TransformationCallback = base::Callback<void(const ViewMatrix&)>;
 
   DesktopViewport();
   ~DesktopViewport();
 
-  // Sets the |desktop_size_| and initializes the viewport when necessary.
+  // Sets the |desktop_size_| and (re)initializes the viewport.
   void SetDesktopSize(int desktop_width, int desktop_height);
 
-  // Sets the |surface_size_| and initializes the viewport when necessary.
+  // Sets the |surface_size_| and (re)initializes the viewport if both
+  // dimensions are changed.
   void SetSurfaceSize(int surface_width, int surface_height);
 
   // Translates the desktop on the surface's reference frame by <dx, dy>.
   void MoveDesktop(float dx, float dy);
 
   // Scales the desktop on the surface's reference frame at pivot point (px, py)
   // by |scale|.
   void ScaleDesktop(float px, float py, float scale);
 
   // Moves the viewport center by <x, y> on the desktop's coordinate.
@@ skipping 64 matching lines @@
 
   TransformationCallback on_transformation_changed_;
 
   // DesktopViewport is neither copyable nor movable.
   DesktopViewport(const DesktopViewport&) = delete;
   DesktopViewport& operator=(const DesktopViewport&) = delete;
 };
 
 }  // namespace remoting
 #endif  // REMOTING_CLIENT_UI_DESKTOP_VIEWPORT_H_