Create APIReview_UAString

Author: jasonstephen15

specs/APIReview_UAString

@@ -0,0 +1,149 @@
+The purpose of this spec is to describe a new WebView2 feature - Support for UA Strings - and its APIs.
+
+# Background
+
+A User Agent String is a client-side piece of information that the browser/webcontrol sends to the server/website a user visits. 
+It contains information about user’s system and is modifiable by the user.  
+
+Currently, a developer can pass the --user-agent browser args to the CreateWebView2EnvironmentWithDetails function. 
+	Ex. CreateWebView2EnvironmentWithDetails(nullptr, nullptr, L"--user-agent=\"myUA\"", ...); 
+	For more info about the ‘—user-agent’ flag visit: https://peter.sh/experiments/chromium-command-line-switches/#user-agent.  
+
+However, there is a limitation to this workaround, in that you cannot modify a command line switch at runtime.  
+
+In this document we describe the new API. We'd appreciate your feedback.
+
+
+# Description
+
+There are 2 locations for changing UA String in a WebView context: 
+
+1. Settings – Changes UA per WebView2 via Chrome Developer Protocol. (CDP) 
+2. Environment Options – sets UA once at creation for the WebView2 environment.
+
+We wanted to create an API that handles #1?? or #2? //jason to update
+We added an API that allows a user to ...
+
+# Examples
+<!-- TEMPLATE
+    Use this section to explain the features of the API, showing
+    example code with each description in both C# (for our WinRT API or .NET API) and
+    in C++ for our COM API. Use snippets of the sample code you wrote for the sample apps.
+
+    The general format is:
+
+    ## FirstFeatureName
+
+    Feature explanation text goes here, including why an app would use it, how it
+    replaces or supplements existing functionality.
+
+    ```c#
+    void SampleMethod()
+    {
+        var show = new AnExampleOf();
+        show.SomeMembers = AndWhyItMight(be, interesting)
+    }
+    ```
+    
+    ```cpp
+    void SampleClass::SampleMethod()
+    {
+        winrt::com_ptr<ICoreWebView2> webview2 = ...
+    }
+    ```
+
+    ## SecondFeatureName
+
+    Feature explanation text goes here, including why an app would use it, how it
+    replaces or supplements existing functionality.
+
+    ```c#
+    void SampleMethod()
+    {
+        var show = new AnExampleOf();
+        show.SomeMembers = AndWhyItMight(be, interesting)
+    }
+    ```
+    
+    ```cpp
+    void SampleClass::SampleMethod()
+    {
+        winrt::com_ptr<ICoreWebView2> webview2 = ...
+    }
+    ```
+
+    As an example of this section, see the Examples section for the PasswordBox
+    control (https://docs.microsoft.com/windows/uwp/design/controls-and-patterns/password-box#examples). 
+-->
+
+
+# Remarks
+<!-- TEMPLATE
+    Explanation and guidance that doesn't fit into the Examples section.
+
+    APIs should only throw exceptions in exceptional conditions; basically,
+    only when there's a bug in the caller, such as argument exception.  But if for some
+    reason it's necessary for a caller to catch an exception from an API, call that
+    out with an explanation either here or in the Examples
+-->
+
+
+# API Notes
+<!-- TEMPLATE
+    Option 1: Give a one or two line description of each API (type and member),
+        or at least the ones that aren't obvious from their name. These
+        descriptions are what show up in IntelliSense. For properties, specify
+        the default value of the property if it isn't the type's default (for
+        example an int-typed property that doesn't default to zero.) 
+        
+    Option 2: Put these descriptions in the below API Details section,
+        with a "///" comment above the member or type. 
+-->
+
+
+# API Details
+<!-- TEMPLATE
+    The exact API, in IDL format for our COM API and
+    in MIDL3 format (https://docs.microsoft.com/en-us/uwp/midl-3/)
+    when possible, or in C# if starting with an API sketch for our .NET and WinRT API.
+
+    Include every new or modified type but use // ... to remove any methods,
+    properties, or events that are unchanged.
+
+    (GitHub's markdown syntax formatter does not (yet) know about MIDL3, so
+    use ```c# instead even when writing MIDL3.)
+
+    Example:
+    
+    ```
+    /// Event args for the NewWindowRequested event. The event is fired when content
+    /// inside webview requested to open a new window (through window.open() and so on.)
+    [uuid(34acb11c-fc37-4418-9132-f9c21d1eafb9), object, pointer_default(unique)]
+    interface ICoreWebView2NewWindowRequestedEventArgs : IUnknown
+    {
+        // ...
+
+        /// Window features specified by the window.open call.
+        /// These features can be considered for positioning and sizing of
+        /// new webview windows.
+        [propget] HRESULT WindowFeatures([out, retval] ICoreWebView2WindowFeatures** windowFeatures);
+    }
+    ```
+
+    ```c# (but really MIDL3)
+    public class CoreWebView2NewWindowRequestedEventArgs
+    {
+        // ...
+
+	       public CoreWebView2WindowFeatures WindowFeatures { get; }
+    }
+    ```
+-->
+
+
+# Appendix
+<!-- TEMPLATE
+    Anything else that you want to write down for posterity, but
+    that isn't necessary to understand the purpose and usage of the API.
+    For example, implementation details or links to other resources.
+-->