Added protocol selection and fixing included 1-3 RC protocol definition

Author: holsee

README.md

@@ -19,6 +19,25 @@ def deps do
 end
 ```
 
+### Chrome DevTools Protocol Selection
+
+Chrome Remote Interface generated its API at compile time from the protocol
+definition released by the Chrome DevTools Team.
+For more info see: [https://chromedevtools.github.io/devtools-protocol/](https://chromedevtools.github.io/devtools-protocol/)
+
+This can be overridden by setting `CRI_PROTOCOL_VERSION` environment variable
+to:
+* 1-2
+* 1-3 * default
+* tot
+
+Example:
+```
+CRI_PROTOCOL_VERSION=1-2 mix compile
+CRI_PROTOCOL_VERSION=1-3 mix compile
+CRI_PROTOCOL_VERSION=tot mix compile
+```
+
 ## Usage
 
 > Note: In these examples, it assumes you're already running chrome headless with remote debugging enabled.

lib/chrome_remote_interface.ex

@@ -5,10 +5,29 @@ defmodule ChromeRemoteInterface do
 
   alias ChromeRemoteInterface.PageSession
 
+  @protocol_env_key "CRI_PROTOCOL_VERSION"
+  @protocol_versions ["1-2", "1-3", "tot"]
+  @protocol_version (
+    if (vsn = System.get_env(@protocol_env_key)) in @protocol_versions do
+      vsn
+    else
+      "1-3"
+    end
+  )
+  IO.puts("Compiling ChromeRemoteInterface with Chrome DevTools Protocol version: '#{@protocol_version}'")
+
+  @doc """
+  Gets the current version of the Chrome Debugger Protocol
+  """
+  def protocol_version() do
+    @protocol_version
+  end
+
   protocol =
-    File.read!("priv/protocol.json")
+    File.read!("priv/#{@protocol_version}/protocol.json")
     |> Poison.decode!()
 
+
   # Generate ChromeRemoteInterface.RPC Modules
 
   Enum.each(protocol["domains"], fn(domain) ->
@@ -58,10 +77,4 @@ defmodule ChromeRemoteInterface do
       end
     end
   end)
-
-  @protocol_version "#{protocol["version"]["major"]}.#{protocol["version"]["minor"]}"
-  @doc """
-  Gets the current version of the Chrome Debugger Protocol
-  """
-  def protocol_version(), do: @protocol_version
 end