[NaCl SDK] docs: Introduce .bc vs .pexe naming convention before using that in doc.

native_client_sdk/doc_generated/devguide/devcycle/debugging.html

 {{+bindTo:partials.standard_nacl_article}}
 
 <section id="debugging">
 <span id="devcycle-debugging"></span><h1 id="debugging"><span id="devcycle-debugging"></span>Debugging</h1>
 <p>This document describes tools and techniques you can use to debug, monitor,
 and measure your application&#8217;s performance.</p>
 <div class="contents local" id="table-of-contents" style="display: none">
 <p class="topic-title first">Table Of Contents</p>
 <ul class="small-gap">
 <li><p class="first"><a class="reference internal" href="#diagnostic-information" id="id2">Diagnostic information</a></p>
@@ skipping 198 matching lines @@
 <p>Note that this same copy of GDB can be used to debug any NaCl program,
 whether built using newlib or glibc for x86-32, x86-64 or ARM.  In the SDK,
 <code>i686-nacl-gdb</code> is an alias for <code>x86_64-nacl-gdb</code>, and the <code>newlib</code>
 and <code>glibc</code> toolchains both contain the same version of GDB.</p>
 <section id="debugging-pnacl-pexes-with-pepper-35">
 <span id="debugging-pnacl-pexes"></span><h4 id="debugging-pnacl-pexes-with-pepper-35"><span id="debugging-pnacl-pexes"></span>Debugging PNaCl pexes (with Pepper 35+)</h4>
 <p>If you want to use GDB to debug a program that is compiled with the PNaCl
 toolchain, you must have a copy of the pexe from <strong>before</strong> running
 <code>pnacl-finalize</code>. The <code>pnacl-finalize</code> tool converts LLVM bitcode
 to the stable PNaCl bitcode format, but it also strips out debug
-metadata, which we need for debugging.</p>
+metadata, which we need for debugging. In this section we&#8217;ll give the
+LLVM bitcode file a <code>.bc</code> file extension, and the PNaCl bitcode file
+a <code>.pexe</code> file extension. The actual extension should not matter, but
+it helps distinguish between the two types of files.</p>
 <p><strong>Note</strong> unlike the finalized copy of the pexe, the non-finalized debug copy
 is not considered stable. This means that a debug copy of the PNaCl
 application created by a Pepper N SDK is only guaranteed to run
 with a matching Chrome version N. If the version of the debug bitcode pexe
 does not match that of Chrome then the translation process may fail, and
 you will see and error message in the JavaScript console.</p>
 <p>Also, make sure you are passing the <code>-g</code> <a class="reference internal" href="/native-client/devguide/devcycle/building.html#compile-flags"><em>compile option</em></a> to <code>pnacl-clang</code> to enable generating debugging info.
 You might also want to omit <code>-O2</code> from the compile-time and link-time
 options, otherwise GDB not might be able to print variables&#8217; values when
 debugging (this is more of a problem with the PNaCl/LLVM toolchain than
@@ skipping 314 matching lines @@
 build a module into a .DLL.</p>
 <section id="open-source-profiling-tools">
 <h3 id="open-source-profiling-tools">Open source profiling tools</h3>
 <p>For the brave-hearted there are open source tools at <a class="reference external" href="http://www.chromium.org/nativeclient">Chromium.org</a> that describe how to do profiling on
 <a class="reference external" href="https://sites.google.com/a/chromium.org/dev/nativeclient/how-tos/profiling-nacl-apps-on-64-bit-windows">64-bit Windows</a>
 and <a class="reference external" href="http://www.chromium.org/nativeclient/how-tos/limited-profiling-with-oprofile-on-x86-64">Linux</a>
 machines.</p>
 </section></section></section>
 
 {{/partials.standard_nacl_article}}