Define Chromoting's differ block size in one (and only one) place.

remoting/host/differ_block.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "remoting/host/differ_block.h"
 
 #include "build/build_config.h"
 #include "media/base/cpu_features.h"
 #include "remoting/host/differ_block_internal.h"
 
 namespace remoting {
 
 int BlockDifference_C(const uint8* image1, const uint8* image2, int stride) {
-  int width_bytes = kBlockWidth * kBytesPerPixel;
+  int width_bytes = kBlockSize * kBytesPerPixel;
 
-  for (int y = 0; y < kBlockHeight; y++) {
+  for (int y = 0; y < kBlockSize; y++) {
     if (memcmp(image1, image2, width_bytes) != 0)
       return 1;
     image1 += stride;
     image2 += stride;
   }
   return 0;
 }
 
 int BlockDifference(const uint8* image1, const uint8* image2, int stride) {
   static int (*diff_proc)(const uint8*, const uint8*, int) = NULL;
 
   if (!diff_proc) {
 #if defined(ARCH_CPU_ARM_FAMILY)
     // For ARM processors, always use C version.
     // TODO(hclam): Implement a NEON version.
     diff_proc = &BlockDifference_C;
 #else
     // For x86 processors, check if SSE2 is supported.
-    if (media::hasSSE2() && kBlockWidth == 32)
+    if (media::hasSSE2() && kBlockSize == 32)
       diff_proc = &BlockDifference_SSE2_W32;
-    else if (media::hasSSE2() && kBlockWidth == 16)
+    else if (media::hasSSE2() && kBlockSize == 16)
       diff_proc = &BlockDifference_SSE2_W16;
     else
       diff_proc = &BlockDifference_C;
 #endif
   }
 
   return diff_proc(image1, image2, stride);
 }
 
 }  // namespace remoting