Move directx_sdk_path definition variable into the video_render_module gyp file.

The variable is now:
* Only set and used for Windows (not globally for all platforms)
* Only used in the standalone build (include_internal_video_render == 1)

This means that we can remove the variable from Chrome and that the standalone
win builders should start picking up the local directx folder and turn green
(*crossesfingers*).
Review URL: https://webrtc-codereview.appspot.com/1103014

git-svn-id: http://webrtc.googlecode.com/svn/trunk@3529 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/modules/video_render/video_render.gypi

@@ -119,10 +119,41 @@
             'include_dirs': ['mac',],
           },
         }],
-        ['OS=="win"', {
+        ['OS=="win" and include_internal_video_render==1', {
+          'variables': {
+            # 'directx_sdk_path' will be overridden in the condition block
+            # below, but it must not be declared as empty here since gyp
+            # will check if the first character is '/' for some reason.
+            # If it's empty, we'll get an out-of-bounds error.
+            'directx_sdk_path': 'will_be_overridden',
+            'directx_sdk_default_path': '<(DEPTH)/third_party/directxsdk/files',
+            'conditions': [
+              ['"<!(python <(DEPTH)/build/dir_exists.py <(directx_sdk_default_path))"=="True"', {
+                'directx_sdk_path': '<(DEPTH)/third_party/directxsdk/files',
+              }, {
+                'directx_sdk_path': '$(DXSDK_DIR)',
+              }],
+            ],
+          },
+
           'include_dirs': [
             '<(directx_sdk_path)/Include',
           ],
+
+          'VCLinkerTool': {
+            'conditions': [
+              ['target_arch=="x86"', {
+                'AdditionalLibraryDirectories': [
+                  '<(directx_sdk_path)/Lib/x86',
+                ],
+              }],
+              ['target_arch=="x64"', {
+                'AdditionalLibraryDirectories': [
+                  '<(directx_sdk_path)/Lib/x64',
+                ],
+              }],
+            ],  # conditions
+          },  # VCLinkerTool
         }],
         ['OS!="win" or include_internal_video_render==0', {
           'sources!': [