Improve tracking of bound FBOs in GrGLGpu.

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 c9e280c3cbc8b7478c8d9c25e24b326086df42b8..6bd8e4db6668bfe9cd8e3a34060b200dcf0439e4 100644
--- a/src/gpu/gl/GrGLGpu.h
+++ b/src/gpu/gl/GrGLGpu.h
@@ -244,11 +244,29 @@ private:
     // ensures that such operations don't negatively interact with tracking bound textures.
     void setScratchTextureUnit();
 
-    // bounds is region that may be modified and therefore has to be resolved.
-    // NULL means whole target. Can be an empty rect.
-    void flushRenderTarget(GrGLRenderTarget*, const SkIRect* bounds);
+    // Enumerates the reasons for binding an FBO.
+    enum FBOBinding {
+        kDraw_FBOBinding,
+        kClear_FBOBinding,
+        kDiscard_FBOBinding,
+        kChangeAttachments_FBOBinding,
+        kReadPixels_FBOBinding,
+        kCopyTexSrc_FBOBinding,
+        kBlitSrc_FBOBinding,
+        kBlitDst_FBOBinding,
+    };
+
+    // binds the FBO and returns the GL enum of the framebuffer target it was bound to.
+    GrGLenum bindFBO(FBOBinding, const GrGLFBO*);
+
+    // Tracks dirty area for resolve, and tracks whether mip maps need rebuilding. bounds is the
+    // region that may be modified. NULL means whole surface. Can be an empty rect.
+    void markSurfaceContentsDirty(GrSurface*, const SkIRect* bounds);
+
+    void setViewport(const GrGLIRect& viewport);
 
     void flushStencil(const GrStencilSettings&);
+
     void flushHWAAState(GrRenderTarget* rt, bool useHWAA);
 
     bool configToGLFormats(GrPixelConfig config,
@@ -279,15 +297,14 @@ private:
     bool createRenderTargetObjects(const GrSurfaceDesc&, bool budgeted, GrGLuint texID, 
                                    GrGLRenderTarget::IDDesc*);
 
-    enum TempFBOTarget {
-        kSrc_TempFBOTarget,
-        kDst_TempFBOTarget
-    };
+    static const FBOBinding kInvalidFBOBinding = static_cast<FBOBinding>(-1);
 
-    GrGLuint bindSurfaceAsFBO(GrSurface* surface, GrGLenum fboTarget, GrGLIRect* viewport,
-                              TempFBOTarget tempFBOTarget);
+    // Binds a surface as an FBO. A temporary FBO ID may be used if the surface is not already
+    // a render target. Afterwards unbindSurfaceAsFBOForCopy must be called with the value returned.
+    FBOBinding bindSurfaceAsFBOForCopy(GrSurface*, FBOBinding, GrGLIRect* viewport);
 
-    void unbindTextureFromFBO(GrGLenum fboTarget);
+    // Must be matched with bindSurfaceAsFBOForCopy.
+    void unbindSurfaceAsFBOForCopy(FBOBinding);
 
     GrGLContext fGLContext;
 
@@ -307,10 +324,9 @@ private:
         kUnknown_TriState
     };
 
-    GrGLuint                    fTempSrcFBOID;
-    GrGLuint                    fTempDstFBOID;
-
-    GrGLuint                    fStencilClearFBOID;
+    SkAutoTUnref<GrGLFBO> fTempSrcFBO;
+    SkAutoTUnref<GrGLFBO> fTempDstFBO;
+    SkAutoTUnref<GrGLFBO> fStencilClearFBO;
 
     // last scissor / viewport scissor state seen by the GL.
     struct {
@@ -456,9 +472,14 @@ private:
     GrPipelineBuilder::DrawFace fHWDrawFace;
     TriState                    fHWWriteToColor;
     TriState                    fHWDitherEnabled;
-    uint32_t                    fHWBoundRenderTargetUniqueID;
     SkTArray<uint32_t, true>    fHWBoundTextureUniqueIDs;
 
+    // Track fbo binding state for GL_DRAW_FRAMEBUFFER and GL_READ_FRAMEBUFFER
+    struct HWFBOBinding {
+        SkAutoTUnref<const GrGLFBO> fFBO;
+        void invalidate() { fFBO.reset(NULL); }
+    } fHWFBOBinding[2];
+
     ///@}
 
     // we record what stencil format worked last time to hopefully exit early