Convert SetIsIncognitoProcess to use mojo.

content/common/renderer.mojom

Index: content/common/renderer.mojom
diff --git a/content/common/renderer.mojom b/content/common/renderer.mojom
index 6c7fb6abb946757b3f8bc5cdb246c0a774c4e9c0..f1b7a39bf51cba73efc9e038fe2674f6ca14da8d 100644
--- a/content/common/renderer.mojom
+++ b/content/common/renderer.mojom
@@ -134,6 +134,8 @@ struct UpdateScrollbarThemeParams {
 // The primordial Channel-associated interface implemented by a render process.
 // This should be used for implementing browser-to-renderer control messages
 // which need to retain FIFO with respect to legacy IPC messages.
+//                                                                              
+// See also chrome.mojom.Renderer defined in chrome/common/renderer.mojom.
 interface Renderer {
   // Tells the renderer to create a new view.
   CreateView(CreateViewParams params);