Reland of Use sysroot by default for all linux builds (patchset #1 id:1 of...

Reland of Use sysroot by default for all linux builds (patchset #1 id:1 of https://codereview.chromium.org/1473363002/ )

Reason for revert:
Couldn't reproduce the failure.

Original issue's description:
> Revert of Use sysroot by default for all linux builds (patchset #7 id:120001 of https://codereview.chromium.org/1464983003/ )
>
> Reason for revert:
> Seems to have caused issues with goma: https://code.google.com/p/chromium/issues/detail?id=560973
>
> Original issue's description:
> > Use sysroot by default for all linux builds
> >
> > Using a sysroot was already the default for official
> > build and when cross compiling (e.g. arm, mips, x86-32).
> > This change makes it the default in all cases.
> >
> > The old behavior of building against local
> > system libraries can still be achieved by
> > setting use_sysroot=0
> >
> > BUG=504446
> >
> > Committed: https://crrev.com/a931efd5dc8d8783ce73a64fc641627866b6869d
> > Cr-Commit-Position: refs/heads/master@{#361197}
>
> TBR=dpranke@chromium.org,thestig@chromium.org,thakis@chromium.org
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=504446
>
> Committed: https://crrev.com/05373dc078f0d5d3f2fb1398db9a4008a55d9016
> Cr-Commit-Position: refs/heads/master@{#361405}

TBR=dpranke@chromium.org,thestig@chromium.org,thakis@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=504446

Review URL: https://codereview.chromium.org/1472873004

Cr-Commit-Position: refs/heads/master@{#361411}

build/common.gypi

@@ -88,10 +88,11 @@
           # Enable Wayland display server support.
           'enable_wayland_server%' : 0,
 
-          # Build against pre-built sysroot image on linux.  By default
-          # the sysroot image is only used for Official builds or when cross
-          # compiling.
-          'use_sysroot%': 0,
+          # By default we build against a stable sysroot image to avoid
+          # depending on the packages installed on the local machine. Set this
+          # to 0 to build against locally installed headers and libraries (e.g.
+          # if packaging for a linux distro)
+          'use_sysroot%': 1,
 
           # Override buildtype to select the desired build flavor.
           # Dev - everyday build for development/testing
@@ -294,8 +295,11 @@
             'mips_arch_variant%': 'r1',
           }],
 
-          # The system root for cross-compiles. Default: none.
-          ['OS=="linux" and chromeos==0 and ((branding=="Chrome" and buildtype=="Official") or target_arch=="arm" or target_arch=="mipsel" or use_sysroot==1)', {
+          # The system root for linux compiles.
+          # Not used when chromecast=1 since ozone_platform_gbm doesn't
+          # currently build against the linux sysroot
+          # TODO(sbc): http://crbug.com/559708
+          ['OS=="linux" and chromeos==0 and chromecast==0 and use_sysroot==1', {
             # sysroot needs to be an absolute path otherwise it generates
             # incorrect results when passed to pkg-config
             'conditions': [

build/config/sysroot.gni

@@ -11,6 +11,7 @@ declare_args() {
   # The absolute path of the sysroot that is applied when compiling using
   # the target toolchain.
   target_sysroot = ""
+  use_sysroot = true
 }
 
 if (current_toolchain == default_toolchain && target_sysroot != "") {
@@ -32,28 +33,23 @@ if (current_toolchain == default_toolchain && target_sysroot != "") {
   } else {
     sysroot = ""
   }
-} else if (is_linux && is_chrome_branded && is_official_build && !is_chromeos) {
-  # For official builds, use the sysroot checked into the internal source repo
-  # so that the builds work on older versions of Linux.
+} else if (is_linux && !is_chromeos && use_sysroot) {
+  # By default build against a sysroot image downloaded from Cloud Storage
+  # during gclient runhooks.
   if (current_cpu == "x64") {
     sysroot = rebase_path("//build/linux/debian_wheezy_amd64-sysroot")
   } else if (current_cpu == "x86") {
     sysroot = rebase_path("//build/linux/debian_wheezy_i386-sysroot")
-  } else {
-    # Any other builds don't use a sysroot.
-    sysroot = ""
-  }
-} else if (is_linux && !is_chromeos) {
-  if (current_cpu == "mipsel") {
-    sysroot = rebase_path("//mipsel-sysroot/sysroot")
+  } else if (current_cpu == "mipsel") {
+    sysroot = rebase_path("//build/linux/debian_wheezy_mips-sysroot")
   } else if (current_cpu == "arm") {
     sysroot = rebase_path("//build/linux/debian_wheezy_arm-sysroot")
   } else {
+    # Any other builds don't use a sysroot.
     sysroot = ""
   }
 } else if (is_mac) {
   import("//build/config/mac/mac_sdk.gni")
-
   sysroot = mac_sdk_path
 } else if (is_ios) {
   import("//build/config/ios/ios_sdk.gni")

build/linux/sysroot_scripts/install-sysroot.py

@@ -103,28 +103,6 @@ def DetectArch(gyp_defines, is_android):
   return None
 
 
-def UsingSysroot(target_arch, is_android, gyp_defines):
-  # ChromeOS uses a chroot, so doesn't need a sysroot
-  if gyp_defines.get('chromeos'):
-    return False
-
-  # When cross-compiling non-Android builds we always use a sysroot
-  if not is_android and target_arch in ('arm', 'mips', 'i386'):
-    return True
-
-  # Setting use_sysroot=1 GYP_DEFINES forces the use of the sysroot even
-  # when not cross compiling
-  if gyp_defines.get('use_sysroot'):
-    return True
-
-  # Official builds always use the sysroot.
-  if (gyp_defines.get('branding') == 'Chrome' and
-      gyp_defines.get('buildtype') == 'Official'):
-    return True
-
-  return False
-
-
 def main():
   if options.running_as_hook and not sys.platform.startswith('linux'):
     return 0
@@ -134,6 +112,10 @@ def main():
   gyp_defines = gyp_chromium.GetGypVars(supplemental_includes)
   is_android = gyp_defines.get('OS') == 'android'
 
+  if (options.running_as_hook and (not is_android) and
+      (gyp_defines.get('chromeos') or gyp_defines.get('use_sysroot') == '0')):
+    return 0
+
   if options.arch:
     target_arch = options.arch
   else:
@@ -142,10 +124,6 @@ def main():
       print 'Unable to detect target architecture'
       return 1
 
-  if (options.running_as_hook and
-      not UsingSysroot(target_arch, is_android, gyp_defines)):
-    return 0
-
   if is_android:
     # 32-bit Android builds require a 32-bit host sysroot for the v8 snapshot.
     if '64' not in target_arch: