Add transfer buffer support.

src/gpu/gl/SkNullGLContext.cpp

Index: src/gpu/gl/SkNullGLContext.cpp
diff --git a/src/gpu/gl/SkNullGLContext.cpp b/src/gpu/gl/SkNullGLContext.cpp
index e2a80ce2b37e72ca6f2c68c85f9a00090c6477b0..e7270c32c47c6283f5d45e4f2be40bb520a0abda 100644
--- a/src/gpu/gl/SkNullGLContext.cpp
+++ b/src/gpu/gl/SkNullGLContext.cpp
@@ -122,6 +122,8 @@ public:
     BufferManager   fBufferManager;
     GrGLuint        fCurrArrayBuffer;
     GrGLuint        fCurrElementArrayBuffer;
+    GrGLuint        fCurrPixelPackBuffer;
+    GrGLuint        fCurrPixelUnpackBuffer;
     GrGLuint        fCurrProgramID;
     GrGLuint        fCurrShaderID;
 
@@ -129,6 +131,8 @@ public:
     ContextState()
         : fCurrArrayBuffer(0)
         , fCurrElementArrayBuffer(0)
+        , fCurrPixelPackBuffer(0)
+        , fCurrPixelUnpackBuffer(0)
         , fCurrProgramID(0)
         , fCurrShaderID(0) {}
 
@@ -172,6 +176,12 @@ GrGLvoid GR_GL_FUNCTION_TYPE nullGLBufferData(GrGLenum target,
     case GR_GL_ELEMENT_ARRAY_BUFFER:
         id = state->fCurrElementArrayBuffer;
         break;
+    case GR_GL_PIXEL_PACK_BUFFER:
+        id = state->fCurrPixelPackBuffer;
+        break;
+    case GR_GL_PIXEL_UNPACK_BUFFER:
+        id = state->fCurrPixelUnpackBuffer;
+        break;
     default:
         SkFAIL("Unexpected target to nullGLBufferData");
         break;
@@ -215,6 +225,12 @@ GrGLvoid GR_GL_FUNCTION_TYPE nullGLBindBuffer(GrGLenum target, GrGLuint buffer)
     case GR_GL_ELEMENT_ARRAY_BUFFER:
         state->fCurrElementArrayBuffer = buffer;
         break;
+    case GR_GL_PIXEL_PACK_BUFFER:
+        state->fCurrPixelPackBuffer = buffer;
+        break;
+    case GR_GL_PIXEL_UNPACK_BUFFER:
+        state->fCurrPixelUnpackBuffer = buffer;
+        break;
     }
 }
 
@@ -228,6 +244,12 @@ GrGLvoid GR_GL_FUNCTION_TYPE nullGLDeleteBuffers(GrGLsizei n, const GrGLuint* id
         if (ids[i] == state->fCurrElementArrayBuffer) {
             state->fCurrElementArrayBuffer = 0;
         }
+        if (ids[i] == state->fCurrPixelPackBuffer) {
+            state->fCurrPixelPackBuffer = 0;
+        }
+        if (ids[i] == state->fCurrPixelUnpackBuffer) {
+            state->fCurrPixelUnpackBuffer = 0;
+        }
 
         BufferObj* buffer = state->fBufferManager.lookUp(ids[i]);
         state->fBufferManager.free(buffer);
@@ -245,6 +267,12 @@ GrGLvoid* GR_GL_FUNCTION_TYPE nullGLMapBufferRange(GrGLenum target, GrGLintptr o
         case GR_GL_ELEMENT_ARRAY_BUFFER:
             id = state->fCurrElementArrayBuffer;
             break;
+        case GR_GL_PIXEL_PACK_BUFFER:
+            id = state->fCurrPixelPackBuffer;
+            break;
+        case GR_GL_PIXEL_UNPACK_BUFFER:
+            id = state->fCurrPixelUnpackBuffer;
+            break;
     }
 
     if (id > 0) {
@@ -267,6 +295,12 @@ GrGLvoid* GR_GL_FUNCTION_TYPE nullGLMapBuffer(GrGLenum target, GrGLenum access)
         case GR_GL_ELEMENT_ARRAY_BUFFER:
             id = state->fCurrElementArrayBuffer;
             break;
+        case GR_GL_PIXEL_PACK_BUFFER:
+            id = state->fCurrPixelPackBuffer;
+            break;
+        case GR_GL_PIXEL_UNPACK_BUFFER:
+            id = state->fCurrPixelUnpackBuffer;
+            break;
     }
 
     if (id > 0) {
@@ -295,6 +329,12 @@ GrGLboolean GR_GL_FUNCTION_TYPE nullGLUnmapBuffer(GrGLenum target) {
     case GR_GL_ELEMENT_ARRAY_BUFFER:
         id = state->fCurrElementArrayBuffer;
         break;
+    case GR_GL_PIXEL_PACK_BUFFER:
+        id = state->fCurrPixelPackBuffer;
+        break;
+    case GR_GL_PIXEL_UNPACK_BUFFER:
+        id = state->fCurrPixelUnpackBuffer;
+        break;
     }
     if (id > 0) {
         BufferObj* buffer = state->fBufferManager.lookUp(id);
@@ -320,6 +360,12 @@ GrGLvoid GR_GL_FUNCTION_TYPE nullGLGetBufferParameteriv(GrGLenum target, GrGLenu
                 case GR_GL_ELEMENT_ARRAY_BUFFER:
                     id = state->fCurrElementArrayBuffer;
                     break;
+                case GR_GL_PIXEL_PACK_BUFFER:
+                    id = state->fCurrPixelPackBuffer;
+                    break;
+                case GR_GL_PIXEL_UNPACK_BUFFER:
+                    id = state->fCurrPixelUnpackBuffer;
+                    break;
             }
             if (id > 0) {
                 BufferObj* buffer = state->fBufferManager.lookUp(id);