Remove inside_chromium_build gyp variable

ppapi/ppapi_internal.gyp

Index: ppapi/ppapi_internal.gyp
diff --git a/ppapi/ppapi_internal.gyp b/ppapi/ppapi_internal.gyp
index 6d7563827404aa77a1a34148d9191c265fb3a346..d9af2e31be587001f38c2fe78c57cd85c490c821 100644
--- a/ppapi/ppapi_internal.gyp
+++ b/ppapi/ppapi_internal.gyp
@@ -54,12 +54,12 @@
         '../skia/skia.gyp:skia',
         '../third_party/icu/icu.gyp:icuuc',
         # TODO(ananta) : The WebKit dependency needs to move to a new target for NACL.
-        '<(webkit_src_dir)/Source/WebKit/chromium/WebKit.gyp:webkit',
+        '../third_party/WebKit/Source/WebKit/chromium/WebKit.gyp:webkit',
         '../ui/surface/surface.gyp:surface',
       ],
       'export_dependent_settings': [
         '../base/base.gyp:base',
-        '<(webkit_src_dir)/Source/WebKit/chromium/WebKit.gyp:webkit',
+        '../third_party/WebKit/Source/WebKit/chromium/WebKit.gyp:webkit',
       ],
       'conditions': [
         ['OS=="mac"', {
@@ -115,7 +115,7 @@
             '../third_party/icu/icu.gyp:icuuc',
             '../third_party/icu/icu.gyp:icui18n',
             # TODO(ananta) : The WebKit dependency needs to move to a new target for NACL.
-            '<(webkit_src_dir)/Source/WebKit/chromium/WebKit.gyp:webkit',
+            '../third_party/WebKit/Source/WebKit/chromium/WebKit.gyp:webkit',
             '../ui/surface/surface.gyp:surface',
             'ppapi.gyp:ppapi_c',
             'ppapi_shared',
@@ -154,7 +154,7 @@
             '../third_party/icu/icu.gyp:icuuc',
             '../third_party/icu/icu.gyp:icui18n',
             # TODO(ananta) : The WebKit dependency needs to move to a new target for NACL.
-            '<(webkit_src_dir)/Source/WebKit/chromium/WebKit.gyp:webkit',
+            '../third_party/WebKit/Source/WebKit/chromium/WebKit.gyp:webkit',
             '../ui/surface/surface.gyp:surface',
             'ppapi.gyp:ppapi_c',
             'ppapi_shared',