linter: Includes should use the full path from the source directory.

Per the Google Style Guide #includes of a project's header files
should be listed as descendants of the project's source directory.

http://google-styleguide.googlecode.com/svn/trunk/cppguide.xml?showone=Names_and_Order_of_Includes#Names_and_Order_of_Includes

In update_engine, all the project's include have the update_engine/
directory prefix.

BUG=None
TEST=Build and unittests pass.

Change-Id: I8ab300491f868723848f76c27a3d2de86598ba2f
Reviewed-on: https://chromium-review.googlesource.com/191180
Reviewed-by: Chris Sosa <sosa@chromium.org>
Commit-Queue: Alex Deymo <deymo@chromium.org>
Tested-by: Alex Deymo <deymo@chromium.org>
Reviewed-by: Don Garrett <dgarrett@chromium.org>
diff --git a/mock_p2p_manager.h b/mock_p2p_manager.h
index 353b904..4d2e9f3 100644
--- a/mock_p2p_manager.h
+++ b/mock_p2p_manager.h
@@ -5,7 +5,7 @@
 #ifndef CHROMEOS_PLATFORM_UPDATE_ENGINE_MOCK_P2P_MANAGER_H_
 #define CHROMEOS_PLATFORM_UPDATE_ENGINE_MOCK_P2P_MANAGER_H_
 
-#include "fake_p2p_manager.h"
+#include "update_engine/fake_p2p_manager.h"
 
 #include <gmock/gmock.h>