ui: No more TestCompositor. Use NullDraw contexts in unit tests.

ui/gl/gl_implementation.h

Index: ui/gl/gl_implementation.h
diff --git a/ui/gl/gl_implementation.h b/ui/gl/gl_implementation.h
index 0881e10b32d378887da20aa30c0ebb3fef96e711..f163e07c1505c3b3ccf91660bbe117a237f18f98 100644
--- a/ui/gl/gl_implementation.h
+++ b/ui/gl/gl_implementation.h
@@ -52,9 +52,21 @@ GL_EXPORT bool InitializeDynamicGLBindings(GLImplementation implementation,
 // Initialize Debug logging wrappers for GL bindings.
 void InitializeDebugGLBindings();
 
-// Initialize stub methods for drawing operations in the GL bindings.
+// Initialize stub methods for drawing operations in the GL bindings. The
+// null draw bindings default to enabled, so that draw operations do nothing.
 void InitializeNullDrawGLBindings();
 
+// Once initialized, instantiating this turns the stub methods for drawing
+// operations off allowing drawing will occur while the object is alive.
+class GL_EXPORT DisableNullDrawGLBindings {

[danakj, 2014/01/29 01:28:21]

I feel like gl_implementation.h should be considered private, and GLSurface is
more like the public API. But that's after spending only a little time in this
space. As such, I feel like this should be exposed in some other way/place, but
I don't really know another more appropriate place. WDYT?

[piman, 2014/01/29 01:40:17]

Bits of this file are definitely used legitimately in other places, like
GetGLImplementation(), or HasDesktopGLFeatures() so this is not completely
crazy.
Maybe we could spend some time to separate the internal vs external bits, but I
think we're fine for now.

+ public:
+  DisableNullDrawGLBindings();
+  ~DisableNullDrawGLBindings();
+
+ private:
+  bool initial_enabled_;
+};
+
 GL_EXPORT void ClearGLBindings();
 
 // Set the current GL implementation.