switch GatherPixelRefs to use SkBaseDevice instead of SkBitmapDevice

include/gpu/SkGpuDevice.h

Index: include/gpu/SkGpuDevice.h
diff --git a/include/gpu/SkGpuDevice.h b/include/gpu/SkGpuDevice.h
index 29f59f28df6a46d1edd3ef45ba14aad31536f742..d37f63d7a0724e9547f55860dfc1b364365b95ff 100644
--- a/include/gpu/SkGpuDevice.h
+++ b/include/gpu/SkGpuDevice.h
@@ -72,7 +72,6 @@ public:
     virtual int height() const SK_OVERRIDE {
         return NULL == fRenderTarget ? 0 : fRenderTarget->height();
     }
-    virtual void getGlobalBounds(SkIRect* bounds) const SK_OVERRIDE;
     virtual bool isOpaque() const SK_OVERRIDE {
         return NULL == fRenderTarget ? false
                                      : kRGB_565_GrPixelConfig == fRenderTarget->config();