Add swapBuffer call to SkGLContextHelper.

include/gpu/gl/SkGLContextHelper.h

 
 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #ifndef SkGLContextHelper_DEFINED
 #define SkGLContextHelper_DEFINED
 
@@ skipping 16 matching lines @@
      * Initializes the context and makes it current.
      */
     bool init(const int width, const int height);
 
     int getFBOID() const { return fFBO; }
 
     const GrGLInterface* gl() const { return fGL; }
 
     virtual void makeCurrent() const = 0;
 
+    /**
+     * If the drawing surface provided by the platform is double buffered this
+     * call will cause the platform to swap with buffer is currently being
+     * targeted.  If the current surface does not include a back buffer, this
+     * call has no effect.

[bsalomon, 2013/10/09 18:17:08]

Maybe we should say that this is mostly used for scheduling work to the GPU
(since all of the subclasses create primary buffers that are tiny and not meant
to be rendered to).

+     */
+    virtual void swapBuffers() const = 0;
+
     bool hasExtension(const char* extensionName) const {
         SkASSERT(NULL != fGL);
         return fExtensions.has(extensionName);
     }
 
 protected:
     /**
      * Subclass implements this to make a GL context. The returned GrGLInterface
      * should be populated with functions compatible with the context. The
      * format and size of backbuffers does not matter since an FBO will be
@@ skipping 21 matching lines @@
  * SK_GL(glCtx, GenTextures(1, &texID));
  */
 #define SK_GL(ctx, X) (ctx).gl()->f ## X;    \
                       SkASSERT(GR_GL_NO_ERROR == (ctx).gl()->fGetError())
 #define SK_GL_RET(ctx, RET, X) (RET) = (ctx).gl()->f ## X;    \
                   SkASSERT(GR_GL_NO_ERROR == (ctx).gl()->fGetError())
 #define SK_GL_NOERRCHECK(ctx, X) (ctx).gl()->f ## X
 #define SK_GL_RET_NOERRCHECK(ctx, RET, X) (RET) = (ctx).gl()->f ## X
 
 #endif