Merge to XFA: Change DEPS hooks paths to include 'pdfium/'.

docs/build.md

 # PDFium
 
 ## Prerequisites
 
 Get the chromium depot tools via the instructions at
 http://www.chromium.org/developers/how-tos/install-depot-tools (this provides
 the gclient utilty needed below).
 
 Also install Python, Subversion, and Git and make sure they're in your path.
 
 ## Get the code
 
+The name of the top-level directory does not matter. In our examples, we use
+"repo". This directory must not have been used before by `gclient config` as
+each directory can only house a single gclient configuration.
+
 ```
-mkdir pdfium
+mkdir repo
+cd repo
+gclient config --unmanaged https://pdfium.googlesource.com/pdfium.git
+gclient sync
 cd pdfium
-gclient config --name . --unmanaged https://pdfium.googlesource.com/pdfium.git
-gclient sync
 ```
 
 ## Generate the build files
 
 We use the GYP library to generate the build files.
 
 At this point, you have two options. The first option is to use the [Ninja]
 (http://martine.github.io/ninja/) build system (also included with the
 depot\_tools checkout). This is the default as of mid-September, 2015.
 Previously, the second option (platform-specific build files) was the default.
@@ skipping 92 matching lines @@
 ```
 git checkout origin/xfa
 git checkout -b merge_branch
 git branch --set-upstream-to=origin/xfa
 git cherry-pick -x <commit hash>
 git commit --amend # add Merge to XFA
 git cl upload
 ```
 
 Then wait for approval, and `git cl land`