Save and temp dst and src FBO on GrGLGpu and use the temp FBOs for copySurface if needed.

src/gpu/gl/GrGLGpu.h

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrGLGpu_DEFINED
 #define GrGLGpu_DEFINED
 
@@ skipping 265 matching lines @@
     // with new data.
     bool uploadCompressedTexData(const GrSurfaceDesc& desc,
                                  const void* data,
                                  bool isNewTexture = true,
                                  int left = 0, int top = 0,
                                  int width = -1, int height = -1);
 
     bool createRenderTargetObjects(const GrSurfaceDesc&, bool budgeted, GrGLuint texID, 
                                    GrGLRenderTarget::IDDesc*);
 
-    GrGLuint bindSurfaceAsFBO(GrSurface* surface, GrGLenum fboTarget, GrGLIRect* viewport);
+    enum TempFBOTarget {
+        kSrc_TempFBOTarget,
+        kDst_TempFBOTarget
+    };
+
+    GrGLuint bindSurfaceAsFBO(GrSurface* surface, GrGLenum fboTarget, GrGLIRect* viewport,
+                              TempFBOTarget tempFBOTarget);
+
+    void unbindTextureFromFBO(GrGLenum fboTarget);
 
     GrGLContext fGLContext;
 
     // GL program-related state
     ProgramCache*               fProgramCache;
     SkAutoTUnref<GrGLProgram>   fCurrentProgram;
 
     ///////////////////////////////////////////////////////////////////////////
     ///@name Caching of GL State
     ///@{
     int                         fHWActiveTextureUnitIdx;
     GrGLuint                    fHWProgramID;
 
     enum TriState {
         kNo_TriState,
         kYes_TriState,
         kUnknown_TriState
     };
 
+    // Temp FBOs
+    struct TempFBO {

[bsalomon, 2015/02/02 21:33:01]

Maybe it'd be better to just have explicit calls in ~GrGpuGL()? Just seems like
a fair amount code here to avoid a couple lines in ~, plus storing a fGpu
per-id.

+        explicit TempFBO(GrGLGpu* gpu) : fID(0), fGpu(gpu) {}
+        ~TempFBO() {
+            if (0 != fID) {
+                GR_GL_CALL(fGpu->glInterface(), DeleteFramebuffers(1, &fID));
+            }
+        }
+        GrGLuint fID;
+        GrGLGpu* fGpu;
+
+        void reset() {
+            fID = 0;
+        }
+    };
+    TempFBO                     fTempSrcFBO;
+    TempFBO                     fTempDstFBO;
+
     // last scissor / viewport scissor state seen by the GL.
     struct {
         TriState    fEnabled;
         GrGLIRect   fRect;
         void invalidate() {
             fEnabled = kUnknown_TriState;
             fRect.invalidate();
         }
     } fHWScissorSettings;
 
@@ skipping 138 matching lines @@
 
     // we record what stencil format worked last time to hopefully exit early
     // from our loop that tries stencil formats and calls check fb status.
     int fLastSuccessfulStencilFmtIdx;
 
     typedef GrGpu INHERITED;
     friend class GrGLPathRendering; // For accessing setTextureUnit.
 };
 
 #endif