Unrollback the Scons changes, they weren't the cause of the problem.

build/SConscript.main

 # Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import os
 import shutil
 import sys
 
 
 p = ARGUMENTS.get('PROGRESS')
@@ skipping 219 matching lines @@
 
 
 
 # --------------------------------------------------------------------------
 # Windows specific
 
 windows_env = root_env.Clone()
 environment_list.append(windows_env)
 windows_env.Tool('target_platform_windows')
 windows_env.Tool('target_debug')
+windows_env.Tool('component_targets_msvs')  # Per target project support.
 windows_env.Tool('midl')
 windows_env.Replace(
     BUILD_TYPE = 'debug-windows',
     BUILD_TYPE_DESCRIPTION = 'Windows debug build',
 )
 windows_env.Append(BUILD_GROUPS = ['default'])
 
 # TODO(bradnelson): this is needed for now because target_platform_windows
 # has OS_WINDOWS defined in a weird way.
 windows_env.FilterOut(CPPDEFINES = ['OS_WINDOWS=OS_WINDOWS'])
@@ skipping 397 matching lines @@
 # Invoke all the SConscripts in each of the environments that make sense on
 # this host-platform.
 BuildComponents(environment_list)
 
 # -------------------------------------------------------------------------
 
 # This must occur after BuildComponents so that the dependency graph
 # will be populated.
 if root_env.Bit('solution'):
   solution_env = root_env.Clone(tools = ['visual_studio_solution'])
-  solution = solution_env.Solution(
-      '$MAIN_DIR/chrome_scons', [windows_env],
+  src_solution = solution_env.Solution(
+      '$MAIN_DIR/chrome_scons_src', [windows_env],
       exclude_pattern = '.*(Program Files|platformsdk_vista_6_0|cygwin).*',
   )
+
+  solution = windows_env.ComponentVSSolution('chrome_scons',
+      [
+           'all_libraries',
+           'all_programs',
+           'all_test_programs',
+      ],
+      projects = [windows_env.File('$MAIN_DIR/chrome_scons_src.vcproj')],
+      COMPONENT_VS_SOLUTION_DIR='$MAIN_DIR',
+      COMPONENT_VS_PROJECT_DIR='$MAIN_DIR/projects',
+      COMPONENT_VS_PROJECT_SCRIPT_PATH=(
+        'cd $$(ProjectDir)/$VS_PROJECT_TO_MAIN_DIR && hammer.bat'),
+  )
+
   Default(None)  # Delete all other default targets.
-  Default(solution)  # Build just the solution.
+  Default([src_solution, solution])  # Build just the solution.
 
 # -------------------------------------------------------------------------