Add the pdf plugin's source in src\pdf.

chrome/chrome_exe.gypi

Index: chrome/chrome_exe.gypi
===================================================================
--- chrome/chrome_exe.gypi	(revision 271525)
+++ chrome/chrome_exe.gypi	(working copy)
@@ -368,7 +368,7 @@
                          '--breakpad=0',
                          '--keystone=<(mac_keystone)',
                          '--scm=1',
-                         '--pdf=<(internal_pdf)',
+                         '--pdf=1',
                          '--bundle_id=<(mac_bundle_id)'],
             },
             {
@@ -430,23 +430,17 @@
             # chrome/app/theme/google_chrome/BRANDING have the short name
             # "chrome" etc.; should we try to extract from there instead?
 
-            # On Mac, this is done in chrome_dll.gypi.
-            ['internal_pdf', {
+            # CrOS does this in a separate build step.
+            ['OS=="linux" and chromeos==0 and linux_dump_symbols==1', {
               'dependencies': [
-                '../pdf/pdf.gyp:pdf',
+                '../pdf/pdf.gyp:pdf_linux_symbols',
               ],
-              'conditions': [
-                # CrOS does this in a separate build step.
-                ['OS=="linux" and chromeos==0 and linux_dump_symbols==1', {
-                  'dependencies': [
-                    '../pdf/pdf.gyp:pdf_linux_symbols',
-                  ],
-                }], # OS=="linux" and chromeos==0 and linux_dump_symbols==1
-              ],
-            }], # internal_pdf
+            }], # OS=="linux" and chromeos==0 and linux_dump_symbols==1
           ],
           'dependencies': [
             '../components/components.gyp:startup_metric_utils',
+            # On Mac, this is done in chrome_dll.gypi.
+            '../pdf/pdf.gyp:pdf',
             'chrome_resources.gyp:packed_extra_resources',
             'chrome_resources.gyp:packed_resources',
             # Copy Flash Player files to PRODUCT_DIR if applicable. Let the .gyp