diff --git a/gpu/include/GrGLInterface.h b/gpu/include/GrGLInterface.h
index 5802ec4f3b..e3942cd203 100644
--- a/gpu/include/GrGLInterface.h
+++ b/gpu/include/GrGLInterface.h
@@ -205,8 +205,8 @@ extern "C" {
     typedef GrGLvoid (GR_GL_FUNCTION_TYPE *GrGLBindFragDataLocationIndexedProc)(GrGLuint program, GrGLuint colorNumber, GrGLuint index, const GrGLchar * name);
 }  // extern "C"
 
-enum GrGLBug {
-    kProbe_GrGLBug = -1
+enum GrGLCapability {
+    kProbe_GrGLCapability = -1
 };
 
 /*
@@ -226,12 +226,12 @@ struct GrGLInterface {
     GrGLBinding fBindingsExported;
 
     /// Does this GL support NPOT textures on FBOs?
-    /// boolean value, or kProbe_GrGLBug to probe (slowly) at context creation.
+    /// boolean value, or kProbe_GrGLCapability to probe (slowly) at context creation.
     int fNPOTRenderTargetSupport;
 
     /// Some GL implementations (PowerVR SGX devices like the iPhone 4)
     /// have restrictions on the size of small render targets.
-    /// kProbe_GrGLBug to probe (slowly) at context creation.
+    /// kProbe_GrGLCapability to probe (slowly) at context creation.
     int fMinRenderTargetHeight;
     int fMinRenderTargetWidth;
 
diff --git a/gpu/src/GrGpuGL.cpp b/gpu/src/GrGpuGL.cpp
index 973e1e4a53..e40024a837 100644
--- a/gpu/src/GrGpuGL.cpp
+++ b/gpu/src/GrGpuGL.cpp
@@ -471,11 +471,13 @@ GrGpuGL::GrGpuGL() {
     // TODO: Make these a preprocess that generate some compile time constants.
     // TODO: probe once at startup, rather than once per context creation.
 
-    if (GrGLGetGLInterface()->fNPOTRenderTargetSupport < 0) {
+    int expectNPOTTargets = GrGLGetGLInterface()->fNPOTRenderTargetSupport;
+    if (expectNPOTTargets == kProbe_GrGLCapability) {
         fNPOTRenderTargetSupport =
             probe_for_npot_render_target_support(fNPOTTextureSupport);
     } else {
-        fNPOTRenderTargetSupport = GrGLGetGLInterface()->fNPOTRenderTargetSupport;
+        GrAssert(expectNPOTTargets == 0 || expectNPOTTargets == 1);
+        fNPOTRenderTargetSupport = static_cast<bool>(expectNPOTTargets);
     }
 
     if (gPrintStartupSpew) {
@@ -503,14 +505,14 @@ GrGpuGL::GrGpuGL() {
     fMaxRenderTargetSize = GrMin(fMaxTextureSize, fMaxRenderTargetSize);
 
     fMinRenderTargetHeight = GrGLGetGLInterface()->fMinRenderTargetHeight;
-    if (fMinRenderTargetHeight < 0) {
+    if (fMinRenderTargetHeight == kProbe_GrGLCapability) {
         fMinRenderTargetHeight =
             probe_for_min_render_target_height(fNPOTRenderTargetSupport,
                                                fMaxRenderTargetSize);
     }
 
     fMinRenderTargetWidth = GrGLGetGLInterface()->fMinRenderTargetWidth;
-    if (fMinRenderTargetWidth < 0) {
+    if (fMinRenderTargetWidth == kProbe_GrGLCapability) {
         fMinRenderTargetWidth =
             probe_for_min_render_target_width(fNPOTRenderTargetSupport,
                                               fMaxRenderTargetSize);
diff --git a/gpu/src/android/GrGLDefaultInterface_android.cpp b/gpu/src/android/GrGLDefaultInterface_android.cpp
index 54bc2f60d3..4c06f17770 100644
--- a/gpu/src/android/GrGLDefaultInterface_android.cpp
+++ b/gpu/src/android/GrGLDefaultInterface_android.cpp
@@ -19,9 +19,9 @@
 void GrGLSetDefaultGLInterface() {
   static GrGLInterface cmd_buffer_interface = {
     kES2_GrGLBinding,
-    kProbe_GrGLBug,  // fNPOTRenderTargetSupport
-    kProbe_GrGLBug,  // fMinRenderTargetHeight
-    kProbe_GrGLBug,  // fMinRenderTargetWidth
+    kProbe_GrGLCapability,  // fNPOTRenderTargetSupport
+    kProbe_GrGLCapability,  // fMinRenderTargetHeight
+    kProbe_GrGLCapability,  // fMinRenderTargetWidth
     glActiveTexture,
     glAttachShader,
     glBindAttribLocation,
diff --git a/gpu/src/mac/GrGLDefaultInterface_mac.cpp b/gpu/src/mac/GrGLDefaultInterface_mac.cpp
index cfa528ab79..d21bdda755 100644
--- a/gpu/src/mac/GrGLDefaultInterface_mac.cpp
+++ b/gpu/src/mac/GrGLDefaultInterface_mac.cpp
@@ -23,9 +23,9 @@ void GrGLSetDefaultGLInterface() {
     static GrGLInterface gDefaultInterface;
     static bool gDefaultInterfaceInit;
     if (!gDefaultInterfaceInit) {
-        gDefaultInterface.fNPOTRenderTargetSupport = true;
-        gDefaultInterface.fMinRenderTargetHeight = 1;
-        gDefaultInterface.fMinRenderTargetWidth = 1;
+        gDefaultInterface.fNPOTRenderTargetSupport = kProbe_GrGLCapability;
+        gDefaultInterface.fMinRenderTargetHeight = kProbe_GrGLCapability;
+        gDefaultInterface.fMinRenderTargetWidth = kProbe_GrGLCapability;
 
         gDefaultInterface.fActiveTexture = glActiveTexture;
         gDefaultInterface.fAttachShader = glAttachShader;
diff --git a/gpu/src/mesa/GrGLDefaultInterface_mesa.cpp b/gpu/src/mesa/GrGLDefaultInterface_mesa.cpp
index bc75a2c4c7..1324649896 100644
--- a/gpu/src/mesa/GrGLDefaultInterface_mesa.cpp
+++ b/gpu/src/mesa/GrGLDefaultInterface_mesa.cpp
@@ -38,9 +38,9 @@ void GrGLSetDefaultGLInterface() {
             // We must have array and element_array buffer objects.
             return;
         }
-        gDefaultInterface.fNPOTRenderTargetSupport = true;
-        gDefaultInterface.fMinRenderTargetHeight = 1;
-        gDefaultInterface.fMinRenderTargetWidth = 1;
+        gDefaultInterface.fNPOTRenderTargetSupport = kProbe_GrGLCapability;
+        gDefaultInterface.fMinRenderTargetHeight = kProbe_GrGLCapability;
+        gDefaultInterface.fMinRenderTargetWidth = kProbe_GrGLCapability;
 
         gDefaultInterface.fActiveTexture = glActiveTexture;
         GR_GL_GET_PROC(AttachShader);
diff --git a/gpu/src/unix/GrGLDefaultInterface_unix.cpp b/gpu/src/unix/GrGLDefaultInterface_unix.cpp
index 2e233e02b2..724f4381dc 100644
--- a/gpu/src/unix/GrGLDefaultInterface_unix.cpp
+++ b/gpu/src/unix/GrGLDefaultInterface_unix.cpp
@@ -40,9 +40,9 @@ void GrGLSetDefaultGLInterface() {
             return;
         }
 
-        gDefaultInterface.fNPOTRenderTargetSupport = true;
-        gDefaultInterface.fMinRenderTargetHeight = 1;
-        gDefaultInterface.fMinRenderTargetWidth = 1;
+        gDefaultInterface.fNPOTRenderTargetSupport = kProbe_GrGLCapability;
+        gDefaultInterface.fMinRenderTargetHeight = kProbe_GrGLCapability;
+        gDefaultInterface.fMinRenderTargetWidth = kProbe_GrGLCapability;
 
         gDefaultInterface.fActiveTexture = glActiveTexture;
         GR_GL_GET_PROC(AttachShader);
diff --git a/gpu/src/win/GrGLDefaultInterface_win.cpp b/gpu/src/win/GrGLDefaultInterface_win.cpp
index 9b40a94edb..3bbd262a64 100644
--- a/gpu/src/win/GrGLDefaultInterface_win.cpp
+++ b/gpu/src/win/GrGLDefaultInterface_win.cpp
@@ -45,9 +45,9 @@ void GrGLSetDefaultGLInterface() {
                 return;
             }
 
-            gDefaultInterface.fNPOTRenderTargetSupport = true;
-            gDefaultInterface.fMinRenderTargetHeight = 1;
-            gDefaultInterface.fMinRenderTargetWidth = 1;
+            gDefaultInterface.fNPOTRenderTargetSupport = kProbe_GrGLCapability;
+            gDefaultInterface.fMinRenderTargetHeight = kProbe_GrGLCapability;
+            gDefaultInterface.fMinRenderTargetWidth = kProbe_GrGLCapability;
 
             // Functions that are part of GL 1.1 will return NULL in
             // wglGetProcAddress