Move DevTools out of ash and turn it to a component.

components/ui_devtools/devtools_client.h

Index: components/ui_devtools/devtools_client.h
diff --git a/components/ui_devtools/devtools_client.h b/components/ui_devtools/devtools_client.h
index 1812556154966832f9c084cc061773b1a02333a2..70b5cafd6a967ca124e2e058061fd5b21f6d5d6b 100644
--- a/components/ui_devtools/devtools_client.h
+++ b/components/ui_devtools/devtools_client.h
@@ -11,6 +11,7 @@
 #include "components/ui_devtools/Forward.h"
 #include "components/ui_devtools/Protocol.h"
 #include "components/ui_devtools/devtools_base_agent.h"
+#include "components/ui_devtools/devtools_export.h"
 
 namespace ui {
 namespace devtools {
@@ -21,7 +22,7 @@ class UiDevToolsServer;
 // this class and attach the corresponding backends/frontends (i.e: DOM, CSS,
 // etc). This client is then attached to the UiDevToolsServer and all messages
 // from this client are sent over the web socket owned by the server.
-class UiDevToolsClient : public protocol::FrontendChannel {
+class UI_DEVTOOLS_EXPORT UiDevToolsClient : public protocol::FrontendChannel {
  public:
   static const int kNotConnected = -1;