Make git version numbers external to batch script.

R=stip@chromium.org, phajdan.jr@chromium.org
BUG=635421

Review URL: https://codereview.chromium.org/2249163005 .

bootstrap/win/README.md

@@ -38,11 +38,11 @@ releases.
     1. Upload those to the gs://chrome-infra Google Storage bucket.
     1. Set the `allUsers Reader` permission (click the "Public link" checkbox
        next to the binaries).
-  1. Edit the `set GIT_VERSION=X.Y.Z` line in `win_tools.bat` to be the new
-     version.
-    1. At the time of writing, the first version is the default version, and
-       the second is the 'bleeding edge' version. You can use the bleeding edge
-       version to get early feedback/stage a rollout/etc.
+  1. Edit the `git_version.txt` or `git_version_bleeding_edge.txt` file to
+     be the new version.
+    1. You can use the bleeding edge version to get early feedback/stage a
+       rollout/etc. Users can select this version by 'touch'ing the
+       `.git_bleeding_edge` file in the root depot_tools directory.
   1. Commit the CL.
 
 Note that in order for the update to take effect, `gclient` currently needs to

bootstrap/win/git_version.txt

@@ -0,0 +1 @@
+2.8.3

bootstrap/win/git_version_bleeding_edge.txt

@@ -0,0 +1 @@
+2.8.3

bootstrap/win/win_tools.bat

@@ -68,9 +68,9 @@ set FIND_EXE=%SYSTEMROOT%\System32\find.exe
 reg Query "HKLM\Hardware\Description\System\CentralProcessor\0" | %FIND_EXE% /i "x86" > NUL && (set OS_BITS=32) || (set OS_BITS=64)
 
 if not exist "%WIN_TOOLS_ROOT_DIR%\.git_bleeding_edge" (
-  set GIT_VERSION=2.8.3
+  set /p GIT_VERSION= <"%~dp0git_version.txt"
 ) else (
-  set GIT_VERSION=2.8.3
+  set /p GIT_VERSION= <"%~dp0git_version_bleeding_edge.txt"
 )
 set GIT_VERSION=%GIT_VERSION%-%OS_BITS%