Makes it so a node can only the root of one connection at a time

Makes it so a node can only the root of one connection at a time

This resulted in needing to make structural changes. For example, if
connection 2 has a root of A, and A has the children B and C then if A
is assigned to another connection (by way of the owner calling Embed
again), then connection 2 is told A has been deleted and B and C are
removed as children of A.

Because this does structural changes the server change id is advanced.

BUG=389339
TEST=covered by unit tests
R=ben@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=283663

[Ben Goodger (Google), 2014-07-16 16:59:25]

lgtm

[sky, 2014-07-16 18:27:51]

The CQ bit was checked by sky@chromium.org

[commit-bot: I haz the power, 2014-07-16 18:31:53]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/sky@chromium.org/397803003/20001

[commit-bot: I haz the power, 2014-07-16 19:09:09]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  android_aosp on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/android_aosp/builds/9...)
  android_chromium_gn_compile_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/android_chromium_gn_c...)
  android_clang_dbg on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/android_clang_dbg/bui...)
  android_dbg on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/android_dbg/builds/20...)
  chromium_presubmit on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/chromium_presubmit/bu...)
  ios_dbg_simulator on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/ios_dbg_simulator/bui...)
  ios_rel_device on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/ios_rel_device/builds...)
  ios_rel_device_ninja on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/ios_rel_device_ninja/...)
  linux_chromium_chromeos_clang_dbg on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/linux_chromium_chrome...)
  linux_chromium_chromeos_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/linux_chromium_chrome...)
  linux_chromium_clang_dbg on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/linux_chromium_clang_...)
  linux_chromium_gn_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/linux_chromium_gn_rel...)
  linux_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/linux_chromium_rel/bu...)
  mac_chromium_compile_dbg on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/mac_chromium_compile_...)
  mac_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/mac_chromium_rel/buil...)
  win8_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win8_chromium_rel/bui...)
  win_chromium_compile_dbg on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win_chromium_compile_...)
  win_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win_chromium_rel/buil...)
  win_chromium_x64_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win_chromium_x64_rel/...)

[commit-bot: I haz the power, 2014-07-16 19:15:59]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-07-16 19:16:00]

Try jobs failed on following builders:
  ios_dbg_simulator on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/ios_dbg_simulator/bui...)
  ios_rel_device on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/ios_rel_device/builds...)
  ios_rel_device_ninja on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/ios_rel_device_ninja/...)

[sky, 2014-07-16 19:44:34]

The CQ bit was checked by sky@chromium.org

[commit-bot: I haz the power, 2014-07-16 19:45:56]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/sky@chromium.org/397803003/20001

[commit-bot: I haz the power, 2014-07-16 20:28:43]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  android_aosp on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/android_aosp/builds/9...)
  android_chromium_gn_compile_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/android_chromium_gn_c...)
  android_clang_dbg on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/android_clang_dbg/bui...)
  android_dbg on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/android_dbg/builds/20...)
  chromium_presubmit on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/chromium_presubmit/bu...)
  ios_dbg_simulator on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/ios_dbg_simulator/bui...)
  ios_rel_device on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/ios_rel_device/builds...)
  ios_rel_device_ninja on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/ios_rel_device_ninja/...)
  linux_chromium_chromeos_clang_dbg on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/linux_chromium_chrome...)
  linux_chromium_chromeos_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/linux_chromium_chrome...)
  linux_chromium_clang_dbg on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/linux_chromium_clang_...)
  linux_chromium_gn_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/linux_chromium_gn_rel...)
  linux_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/linux_chromium_rel/bu...)
  mac_chromium_compile_dbg on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/mac_chromium_compile_...)
  mac_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/mac_chromium_rel/buil...)
  win8_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win8_chromium_rel/bui...)
  win_chromium_compile_dbg on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win_chromium_compile_...)
  win_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win_chromium_rel/buil...)
  win_chromium_x64_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win_chromium_x64_rel/...)

[commit-bot: I haz the power, 2014-07-16 20:36:54]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-07-16 20:36:55]

Try jobs failed on following builders:
  android_aosp on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/android_aosp/builds/9...)
  android_chromium_gn_compile_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/android_chromium_gn_c...)
  android_clang_dbg on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/android_clang_dbg/bui...)
  chromium_presubmit on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/chromium_presubmit/bu...)
  ios_dbg_simulator on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/ios_dbg_simulator/bui...)
  ios_rel_device on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/ios_rel_device/builds...)
  ios_rel_device_ninja on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/ios_rel_device_ninja/...)
  linux_chromium_chromeos_clang_dbg on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/linux_chromium_chrome...)
  linux_chromium_chromeos_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/linux_chromium_chrome...)
  linux_chromium_gn_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/linux_chromium_gn_rel...)
  linux_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/linux_chromium_rel/bu...)
  win8_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win8_chromium_rel/bui...)

[sky, 2014-07-16 20:54:44]

The CQ bit was checked by sky@chromium.org

[commit-bot: I haz the power, 2014-07-16 20:59:06]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/sky@chromium.org/397803003/20001

[commit-bot: I haz the power, 2014-07-16 22:06:37]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  android_aosp on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/android_aosp/builds/9...)
  android_chromium_gn_compile_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/android_chromium_gn_c...)
  android_clang_dbg on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/android_clang_dbg/bui...)
  android_dbg on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/android_dbg/builds/20...)
  chromium_presubmit on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/chromium_presubmit/bu...)
  ios_dbg_simulator on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/ios_dbg_simulator/bui...)
  ios_rel_device on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/ios_rel_device/builds...)
  ios_rel_device_ninja on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/ios_rel_device_ninja/...)
  linux_chromium_chromeos_clang_dbg on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/linux_chromium_chrome...)
  linux_chromium_chromeos_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/linux_chromium_chrome...)
  linux_chromium_clang_dbg on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/linux_chromium_clang_...)
  linux_chromium_gn_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/linux_chromium_gn_rel...)
  linux_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/linux_chromium_rel/bu...)
  mac_chromium_compile_dbg on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/mac_chromium_compile_...)
  mac_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/mac_chromium_rel/buil...)
  win8_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win8_chromium_rel/bui...)
  win_chromium_compile_dbg on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win_chromium_compile_...)
  win_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win_chromium_rel/buil...)
  win_chromium_x64_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win_chromium_x64_rel/...)

[commit-bot: I haz the power, 2014-07-16 22:13:56]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-07-16 22:13:57]

Try jobs failed on following builders:
  android_aosp on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/android_aosp/builds/9...)
  android_clang_dbg on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/android_clang_dbg/bui...)
  android_dbg on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/android_dbg/builds/20...)
  chromium_presubmit on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/chromium_presubmit/bu...)
  ios_dbg_simulator on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/ios_dbg_simulator/bui...)
  ios_rel_device on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/ios_rel_device/builds...)
  ios_rel_device_ninja on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/ios_rel_device_ninja/...)
  linux_chromium_clang_dbg on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/linux_chromium_clang_...)
  win8_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win8_chromium_rel/bui...)

[sky, 2014-07-16 22:38:30]

The CQ bit was checked by sky@chromium.org

[commit-bot: I haz the power, 2014-07-16 22:40:27]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/sky@chromium.org/397803003/40001

[commit-bot: I haz the power, 2014-07-17 05:39:41]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  linux_gpu on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/linux_gpu/builds/...)

[commit-bot: I haz the power, 2014-07-17 06:36:13]

Change committed as 283663