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

remoting/client/ui/desktop_viewport.cc

Index: remoting/client/ui/desktop_viewport.cc
diff --git a/remoting/client/ui/desktop_viewport.cc b/remoting/client/ui/desktop_viewport.cc
index c150f1bb6b02f4e58ab31bbc9bf372b1852ef27a..0b243af4bc8e450e69b2b7d7fac0b4d937d36774 100644
--- a/remoting/client/ui/desktop_viewport.cc
+++ b/remoting/client/ui/desktop_viewport.cc
@@ -35,9 +35,27 @@ void DesktopViewport::SetSurfaceSize(int surface_width, int surface_height) {
     return;
   }
 
+  // Only reset the viewport if both dimensions have changed, otherwise keep
+  // the offset and scale and just change the constraint. This is to cover these
+  // use cases:
+  // * Rotation => Reset
+  // * Keyboard => No reset
+  // * Settings menu => No reset
+  //
+  // TODO(yuweih): This is probably too much inferring. Let the caller to decide
+  // when to call ResizeToFit() if things don't work right.
+  bool need_to_reset =
+      surface_width != surface_size_.x && surface_height != surface_size_.y;
+
   surface_size_.x = surface_width;
   surface_size_.y = surface_height;
-  ResizeToFit();
+
+  if (need_to_reset) {
+    ResizeToFit();
+    return;
+  }
+
+  UpdateViewport();
 }
 
 void DesktopViewport::MoveDesktop(float dx, float dy) {