Linux: add GYP variable to use the system libpng.

Since our packagers have been requesting that we support using more
system libraries, I'm starting to commit these sorts of changes.
However, please note that one MUST NOT use the system libpng on, at
least, Ubuntu 64-bit. Because Chromium on Linux is still a 32-bit
build we end up with the 32-bit compat versions of libraries and, on
Ubuntu at least, this includes a very old libpng with security issues.


git-svn-id: svn://svn.chromium.org/chrome/trunk/src@21663 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 90 insertions, 49 deletions

diff --git a/base/gfx/png_decoder.cc b/base/gfx/png_decoder.cc
index fe0bf893..5b27ed8 100644
--- a/base/gfx/png_decoder.cc
+++ b/base/gfx/png_decoder.cc
@@ -8,7 +8,11 @@
 #include "third_party/skia/include/core/SkBitmap.h"
 
 extern "C" {
+#if defined(USE_SYSTEM_LIBPNG)
+#include <png.h>
+#else
 #include "third_party/libpng/png.h"
+#endif
 }
 
 namespace {
diff --git a/base/gfx/png_encoder.cc b/base/gfx/png_encoder.cc
index c342736..10a60c6 100644
--- a/base/gfx/png_encoder.cc
+++ b/base/gfx/png_encoder.cc
@@ -10,7 +10,11 @@
 #include "third_party/skia/include/core/SkUnPreMultiply.h"
 
 extern "C" {
+#if defined(USE_SYSTEM_LIBPNG)
+#include <png.h>
+#else
 #include "third_party/libpng/png.h"
+#endif
 }
 
 namespace {
diff --git a/third_party/libpng/libpng.gyp b/third_party/libpng/libpng.gyp
index 63bd9d7..03320e8 100644
--- a/third_party/libpng/libpng.gyp
+++ b/third_party/libpng/libpng.gyp
@@ -6,55 +6,88 @@
   'includes': [
     '../../build/common.gypi',
   ],
-  'targets': [
-    {
-      'target_name': 'libpng',
-      'type': '<(library)',
-      'dependencies': [
-        '../zlib/zlib.gyp:zlib',
+  'variables': {
+    'use_system_libpng%': 0,
+  },
+  'conditions': [
+    ['use_system_libpng==0', {
+      'targets': [
+        {
+          'target_name': 'libpng',
+          'type': '<(library)',
+          'dependencies': [
+            '../zlib/zlib.gyp:zlib',
+          ],
+          'defines': [
+            'CHROME_PNG_WRITE_SUPPORT',
+            'PNG_USER_CONFIG',
+          ],
+          'msvs_guid': 'C564F145-9172-42C3-BFCB-6014CA97DBCD',
+          'sources': [
+            'png.c',
+            'png.h',
+            'pngconf.h',
+            'pngerror.c',
+            'pnggccrd.c',
+            'pngget.c',
+            'pngmem.c',
+            'pngpread.c',
+            'pngread.c',
+            'pngrio.c',
+            'pngrtran.c',
+            'pngrutil.c',
+            'pngset.c',
+            'pngtrans.c',
+            'pngusr.h',
+            'pngvcrd.c',
+            'pngwio.c',
+            'pngwrite.c',
+            'pngwtran.c',
+            'pngwutil.c',
+          ],
+          'direct_dependent_settings': {
+            'include_dirs': [
+              '.',
+            ],
+            'defines': [
+              'CHROME_PNG_WRITE_SUPPORT',
+              'PNG_USER_CONFIG',
+            ],
+          },
+          'export_dependent_settings': [
+            '../zlib/zlib.gyp:zlib',
+          ],
+          'conditions': [
+            ['OS!="win"', {'product_name': 'png'}],
+          ],
+        },
+      ]
+    }, {
+      'targets': [
+        {
+          'target_name': 'libpng',
+          'type': '<(library)',
+          'dependencies': [
+            '../zlib/zlib.gyp:zlib',
+          ],
+          'defines': [
+            'USE_SYSTEM_LIBPNG',
+          ],
+          'direct_dependent_settings': {
+            'cflags': [
+              '<!@(pkg-config --cflags libpng)',
+            ],
+          },
+          'link_settings': {
+            'ldflags': [
+              '<!@(pkg-config --libs-only-L --libs-only-other libpng)',
+            ],
+            'libraries': [
+              '<!@(pkg-config --libs-only-l libpng)',
+            ],
+          },
+        },
       ],
-      'defines': [
-        'CHROME_PNG_WRITE_SUPPORT',
-        'PNG_USER_CONFIG',
-      ],
-      'msvs_guid': 'C564F145-9172-42C3-BFCB-6014CA97DBCD',
-      'sources': [
-        'png.c',
-        'png.h',
-        'pngconf.h',
-        'pngerror.c',
-        'pnggccrd.c',
-        'pngget.c',
-        'pngmem.c',
-        'pngpread.c',
-        'pngread.c',
-        'pngrio.c',
-        'pngrtran.c',
-        'pngrutil.c',
-        'pngset.c',
-        'pngtrans.c',
-        'pngusr.h',
-        'pngvcrd.c',
-        'pngwio.c',
-        'pngwrite.c',
-        'pngwtran.c',
-        'pngwutil.c',
-      ],
-      'direct_dependent_settings': {
-        'include_dirs': [
-          '.',
-        ],
-        'defines': [
-          'CHROME_PNG_WRITE_SUPPORT',
-          'PNG_USER_CONFIG',
-        ],
-      },
-      'export_dependent_settings': [
-        '../zlib/zlib.gyp:zlib',
-      ],
-      'conditions': [
-        ['OS!="win"', {'product_name': 'png'}],
-      ],
-    },
+    }],
   ],
 }