Move LinkResult to the gl:: namespace.

This is a derived type from gl::Error so makes sense to be there.
Also makes it more accessible than in ProgramImpl.h

BUG=angleproject:1897

Change-Id: Id41b13e5a072745d8c361057f5bef8f152e0452b
Reviewed-on: https://chromium-review.googlesource.com/522872
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>
diff --git a/src/libANGLE/renderer/ProgramImpl.h b/src/libANGLE/renderer/ProgramImpl.h
index 1133a21..a0fe6b9 100644
--- a/src/libANGLE/renderer/ProgramImpl.h
+++ b/src/libANGLE/renderer/ProgramImpl.h
@@ -31,8 +31,6 @@
 namespace rx
 {
 
-using LinkResult = gl::ErrorOrResult<bool>;
-
 class ProgramImpl : angle::NonCopyable
 {
   public:
@@ -40,16 +38,16 @@
     virtual ~ProgramImpl() {}
     virtual void destroy(const gl::Context *context) {}
 
-    virtual LinkResult load(const gl::Context *context,
-                            gl::InfoLog &infoLog,
-                            gl::BinaryInputStream *stream)  = 0;
-    virtual void save(gl::BinaryOutputStream *stream)       = 0;
+    virtual gl::LinkResult load(const gl::Context *context,
+                                gl::InfoLog &infoLog,
+                                gl::BinaryInputStream *stream) = 0;
+    virtual void save(gl::BinaryOutputStream *stream)          = 0;
     virtual void setBinaryRetrievableHint(bool retrievable) = 0;
     virtual void setSeparable(bool separable)               = 0;
 
-    virtual LinkResult link(const gl::Context *context,
-                            const gl::VaryingPacking &packing,
-                            gl::InfoLog &infoLog) = 0;
+    virtual gl::LinkResult link(const gl::Context *context,
+                                const gl::VaryingPacking &packing,
+                                gl::InfoLog &infoLog) = 0;
     virtual GLboolean validate(const gl::Caps &caps, gl::InfoLog *infoLog) = 0;
 
     virtual void setUniform1fv(GLint location, GLsizei count, const GLfloat *v) = 0;