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

src/gpu/gl/GrGLGpu.h

Index: src/gpu/gl/GrGLGpu.h
diff --git a/src/gpu/gl/GrGLGpu.h b/src/gpu/gl/GrGLGpu.h
index c5103ebb1159bde79bdb1c4c8294bdccc8ae713a..3eea6e9ee61d1b7333edaee10c4513b9cf3fc4fe 100644
--- a/src/gpu/gl/GrGLGpu.h
+++ b/src/gpu/gl/GrGLGpu.h
@@ -283,7 +283,15 @@ private:
     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;
 
@@ -303,6 +311,24 @@ private:
         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;