make allocPixels throw on failure

tests/BitmapCopyTest.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmap.h"
 #include "SkRect.h"
 #include "Test.h"
@@ skipping 369 matching lines @@
             int subW = 2;
             int subH = 2;
 
             // Create bitmap to act as source for copies and subsets.
             SkBitmap src, subset;
             SkColorTable* ct = NULL;
             if (kIndex_8_SkColorType == src.colorType()) {
                 ct = init_ctable(kPremul_SkAlphaType);
             }
 
+            int localSubW;
             if (isExtracted[copyCase]) { // A larger image to extract from.
-                src.allocPixels(SkImageInfo::Make(2 * subW + 1, subH,
-                                                  gPairs[i].fColorType,
-                                                  kPremul_SkAlphaType));
+                localSubW = 2 * subW + 1;
             } else { // Tests expect a 2x2 bitmap, so make smaller.
-                src.allocPixels(SkImageInfo::Make(subW, subH,
-                                                  gPairs[i].fColorType,
-                                                  kPremul_SkAlphaType));
+                localSubW = subW;
+            }
+            // could fail if we pass kIndex_8 for the colortype
+            if (src.tryAllocPixels(SkImageInfo::Make(localSubW, subH, gPairs[i].fColorType,
+                                                     kPremul_SkAlphaType))) {
+                // failure is fine, as we will notice later on
             }
             SkSafeUnref(ct);
 
             // Either copy src or extract into 'subset', which is used
             // for subsequent calls to copyPixelsTo/From.
             bool srcReady = false;
             // Test relies on older behavior that extractSubset will fail on
             // kUnknown_SkColorType
             if (kUnknown_SkColorType != src.colorType() &&
                 isExtracted[copyCase]) {
@@ skipping 220 matching lines @@
                         REPORTER_ASSERT(reporter, check_4x4_pixel(dstC, sx, sy));
                     } else {
                         REPORTER_ASSERT(reporter, 0 == dstC);
                     }
                 }
             }
         }
     }
 }