Don't use anonymous namespace in header file.

Anonymous namespace should be forbidden in header files even for the
forward declarations:

* As declarations defined in anonymous namespace are internal linkage, each
translation unit which includes this header will get unique copy, which
wastes space.
* It is easy to violate C++ ODR rule.

Consider the following "foo.h":

```cpp
namespace { class Foo; }
class Bar {
  public:
    Foo* getFoo();
    Foo* foo;
}
```

If the 'foo.h' is included in multiple `.cc` files, the compiler will
put `Foo` into a different anonymous namespace in each `.cc`, which
means there are different definitions of `Foo` in the program (a
violation of the ODR).

brightray/browser/views/inspectable_web_contents_view_views.cc

@@ -178,7 +178,7 @@ void InspectableWebContentsViewViews::SetIsDocked(bool docked) {
 
     views::Widget::InitParams params;
     params.ownership = views::Widget::InitParams::WIDGET_OWNS_NATIVE_WIDGET;
-    params.delegate = GetDevToolsWindowDelegate();
+    params.delegate = devtools_window_delegate_;
     params.bounds = inspectable_web_contents()->GetDevToolsBounds();
 
 #if defined(USE_X11)
@@ -203,7 +203,8 @@ void InspectableWebContentsViewViews::SetContentsResizingStrategy(
 
 void InspectableWebContentsViewViews::SetTitle(const base::string16& title) {
   if (devtools_window_) {
-    GetDevToolsWindowDelegate()->SetWindowTitle(title);
+    static_cast<DevToolsWindowDelegate*>(devtools_window_delegate_)
+        ->SetWindowTitle(title);
     devtools_window_->UpdateWindowTitle();
   }
 }

brightray/browser/views/inspectable_web_contents_view_views.h

@@ -10,14 +10,11 @@
 namespace views {
 class WebView;
 class Widget;
+class WidgetDelegate;
 }
 
 namespace brightray {
 
-namespace { // NOLINT
-class DevToolsWindowDelegate;
-}
-
 class InspectableWebContentsImpl;
 
 class InspectableWebContentsViewViews : public InspectableWebContentsView,
@@ -27,10 +24,6 @@ class InspectableWebContentsViewViews : public InspectableWebContentsView,
       InspectableWebContentsImpl* inspectable_web_contents_impl);
   ~InspectableWebContentsViewViews();
 
-  DevToolsWindowDelegate* GetDevToolsWindowDelegate() const {
-    return devtools_window_delegate_;
-  }
-
   // InspectableWebContentsView:
   views::View* GetView() override;
   views::View* GetWebView() override;
@@ -61,7 +54,7 @@ class InspectableWebContentsViewViews : public InspectableWebContentsView,
 
   DevToolsContentsResizingStrategy strategy_;
   bool devtools_visible_;
-  DevToolsWindowDelegate* devtools_window_delegate_;
+  views::WidgetDelegate* devtools_window_delegate_;
 
   DISALLOW_COPY_AND_ASSIGN(InspectableWebContentsViewViews);
 };