Allow max tile size to be overridden separately from max texture size.

include/gpu/GrCaps.h

Index: include/gpu/GrCaps.h
diff --git a/include/gpu/GrCaps.h b/include/gpu/GrCaps.h
index 811a74ff481d5b9cf429c78572f20bf2f999b0c1..6893dc7b5e03329ad103e29364ac020a95446433 100644
--- a/include/gpu/GrCaps.h
+++ b/include/gpu/GrCaps.h
@@ -189,6 +189,9 @@ public:
 
     int maxRenderTargetSize() const { return fMaxRenderTargetSize; }
     int maxTextureSize() const { return fMaxTextureSize; }
+    /** This is the maximum tile size to use by GPU devices for rendering sw-backed images/bitmaps.
+        It is usually the max texture size, unless we're overriding it for testing. */
+    int maxTileSize() const { SkASSERT(fMaxTileSize <= fMaxTextureSize); return fMaxTileSize; }
 
     // Will be 0 if MSAA is not supported
     int maxSampleCount() const { return fMaxSampleCount; }
@@ -263,6 +266,7 @@ protected:
 
     int fMaxRenderTargetSize;
     int fMaxTextureSize;
+    int fMaxTileSize;
     int fMaxSampleCount;
 
     // The first entry for each config is without msaa and the second is with.