Introduce ui.dll / libui.so for the component build.

build/common.gypi

Index: build/common.gypi
===================================================================
--- build/common.gypi	(revision 91577)
+++ build/common.gypi	(working copy)
@@ -677,6 +677,9 @@
       }, {  # else: branding!="Chrome"
         'defines': ['CHROMIUM_BUILD'],
       }],
+      ['component=="shared_library"', {
+        'defines': ['COMPONENT_BUILD=1'],

[rvargas (doing something else), 2011/07/12 21:40:19]

The consensus of the code review that defined xx_dll was to drop the "=1" part.

+      }],
       ['toolkit_views==1', {
         'defines': ['TOOLKIT_VIEWS=1'],
       }],
@@ -901,6 +904,11 @@
               },
             },
           }],
+          ['OS=="win" and component=="shared_library"', {
+            'msvs_disabled_warnings': [
+              4251,  # class 'std::xx' needs to have dll-interface.
+            ],
+          }],
           ['chromeos!=1', {
             'sources/': [ ['exclude', '_chromeos\\.(h|cc)$'] ]
           }],