Move remaining content test code into the content namespace.

content/test/mock_keyboard.h

Index: content/test/mock_keyboard.h
===================================================================
--- content/test/mock_keyboard.h	(revision 164732)
+++ content/test/mock_keyboard.h	(working copy)
@@ -13,6 +13,8 @@
 #include "content/test/mock_keyboard_driver_win.h"
 #endif
 
+namespace content {
+
 // A mock keyboard interface.
 // This class defines a pseudo keyboard device, which implements mappings from
 // a tuple (layout, key code, modifiers) to Unicode characters so that
@@ -103,4 +105,6 @@
   DISALLOW_COPY_AND_ASSIGN(MockKeyboard);
 };
 
+}  // namespace content
+
 #endif  // CONTENT_TEST_MOCK_KEYBOARD_H_