update_engine: Remove the duplicate BlocksInExtents

This patch removes the duplicate BlocksInExtents from extent_utils.h and fixes
the remainder of the code to reflect this change.

BUG=none
TEST=unittests pass;

Change-Id: I76f5106f75072b20cd8f41f081b2f2b07aeac9a8
Reviewed-on: https://chromium-review.googlesource.com/812009
Commit-Ready: Amin Hassani <ahassani@chromium.org>
Tested-by: Amin Hassani <ahassani@chromium.org>
Reviewed-by: Ben Chan <benchan@chromium.org>
Reviewed-by: Alex Deymo <deymo@google.com>
Reviewed-by: Sen Jiang <senj@chromium.org>
diff --git a/payload_generator/ext2_filesystem.cc b/payload_generator/ext2_filesystem.cc
index b884021..07ec371 100644
--- a/payload_generator/ext2_filesystem.cc
+++ b/payload_generator/ext2_filesystem.cc
@@ -18,7 +18,7 @@
 
 #include <et/com_err.h>
 #if defined(__clang__)
-// TODO: Remove these pragmas when b/35721782 is fixed.
+// TODO(*): Remove these pragmas when b/35721782 is fixed.
 #pragma clang diagnostic push
 #pragma clang diagnostic ignored "-Wmacro-redefined"
 #endif
@@ -348,7 +348,7 @@
     return false;
 
   brillo::Blob blob;
-  uint64_t physical_size = BlocksInExtents(extents) * filsys_->blocksize;
+  uint64_t physical_size = utils::BlocksInExtents(extents) * filsys_->blocksize;
   // Sparse holes in the settings file are not supported.
   if (EXT2_I_SIZE(&ino_data) > physical_size)
     return false;