Make instantiate return a Boolean

From an off-line conversation:
The longer term idea will be to create a helper class isolates the
ability to instantiate proxies until flush time. The peek* methods
could then be moved to GrSurfaceProxy.

Change-Id: I8e8c02c098475b77d515791c0d6b81f7e4a327dd
Reviewed-on: https://skia-review.googlesource.com/18076
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
diff --git a/include/private/GrSurfaceProxy.h b/include/private/GrSurfaceProxy.h
index be8c194..bded2c1 100644
--- a/include/private/GrSurfaceProxy.h
+++ b/include/private/GrSurfaceProxy.h
@@ -244,7 +244,7 @@
      */
     UniqueID uniqueID() const { return fUniqueID; }
 
-    virtual GrSurface* instantiate(GrResourceProvider* resourceProvider) = 0;
+    virtual bool instantiate(GrResourceProvider* resourceProvider) = 0;
 
     /**
      * Helper that gets the width and height of the surface as a bounding rectangle.
@@ -347,9 +347,9 @@
         return this->internalHasPendingWrite();
     }
 
-    GrSurface* instantiateImpl(GrResourceProvider* resourceProvider, int sampleCnt,
-                               GrSurfaceFlags flags, bool isMipMapped,
-                               SkDestinationSurfaceColorMode mipColorMode);
+    bool instantiateImpl(GrResourceProvider* resourceProvider, int sampleCnt,
+                         GrSurfaceFlags flags, bool isMipMapped,
+                         SkDestinationSurfaceColorMode mipColorMode);
 
     // For wrapped resources, 'fConfig', 'fWidth', 'fHeight', and 'fOrigin; will always be filled in
     // from the wrapped resource.