Make gtk2/gtk3 compile time switchable.

This adds a "use_gtk3" gyp/gn flag, along with a separate gtk2/gtk3
targets in system.gyp and //build/config/linux/gtk[23] in gn.

BUG=132847

Review URL: https://codereview.chromium.org/1293073006

Cr-Original-Commit-Position: refs/heads/master@{#346742}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: b8f8f682a82bce992edb35c3030214ede236d3ba

common.gypi

@@ -702,6 +702,9 @@
       # Libxkbcommon usage.
       'use_xkbcommon%': 0,
 
+      # Whether we use GTKv3 on linux.
+      'use_gtk3%': 0,
+
       # Control Flow Integrity for virtual calls and casts.
       # See http://clang.llvm.org/docs/ControlFlowIntegrity.html
       'cfi_vptr%': 0,
@@ -1138,6 +1141,7 @@
     'use_ozone%': '<(use_ozone)',
     'use_ozone_evdev%': '<(use_ozone_evdev)',
     'use_xkbcommon%': '<(use_xkbcommon)',
+    'use_gtk3%': '<(use_gtk3)',
     'use_clipboard_aurax11%': '<(use_clipboard_aurax11)',
     'desktop_linux%': '<(desktop_linux)',
     'use_x11%': '<(use_x11)',

config/linux/gtk2/BUILD.gn

@@ -6,12 +6,12 @@ import("//build/config/linux/pkg_config.gni")
 
 assert(is_linux, "This file should only be referenced on Linux")
 
-# Depend on //build/config/linux/gtk to use GTK.
+# Depend on //build/config/linux/gtk2 to use GTKv2.
 #
 # GN doesn't check visibility for configs so we give this an obviously internal
 # name to discourage random targets from accidentally depending on this and
 # bypassing the GTK target's visibility.
-pkg_config("gtk_internal_config") {
+pkg_config("gtk2_internal_config") {
   # Gtk requires gmodule, but it does not list it as a dependency in some
   # misconfigured systems.
   packages = [
@@ -23,7 +23,7 @@ pkg_config("gtk_internal_config") {
 
 # Basically no parts of Chrome should depend on GTK. To prevent accidents, the
 # parts that explicitly need GTK are whitelisted on this target.
-group("gtk") {
+group("gtk2") {
   visibility = [
     "//chrome/browser/ui/libgtk2ui",
     "//gpu/gles2_conform_support:gles2_conform_test_windowless",
@@ -31,15 +31,15 @@ group("gtk") {
     "//remoting/host/it2me:remote_assistance_host",
     "//remoting/host:remoting_me2me_host_static",
   ]
-  public_configs = [ ":gtk_internal_config" ]
+  public_configs = [ ":gtk2_internal_config" ]
 }
 
 # Depend on "gtkprint" to get this.
-pkg_config("gtkprint_internal_config") {
+pkg_config("gtkprint2_internal_config") {
   packages = [ "gtk+-unix-print-2.0" ]
 }
 
-group("gtkprint") {
+group("gtkprint2") {
   visibility = [ "//chrome/browser/ui/libgtk2ui" ]
-  public_configs = [ ":gtkprint_internal_config" ]
+  public_configs = [ ":gtkprint2_internal_config" ]
 }

config/linux/gtk3/BUILD.gn

@@ -0,0 +1,45 @@
+# Copyright 2015 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import("//build/config/linux/pkg_config.gni")
+
+assert(is_linux, "This file should only be referenced on Linux")
+
+# Depend on //build/config/linux/gtk3 to use GTKv3.
+#
+# GN doesn't check visibility for configs so we give this an obviously internal
+# name to discourage random targets from accidentally depending on this and
+# bypassing the GTK target's visibility.
+pkg_config("gtk3_internal_config") {
+  # Gtk requires gmodule, but it does not list it as a dependency in some
+  # misconfigured systems.
+  packages = [
+    "gmodule-2.0",
+    "gtk+-3.0",
+    "gthread-2.0",
+  ]
+}
+
+# Basically no parts of Chrome should depend on GTK. To prevent accidents, the
+# parts that explicitly need GTK are whitelisted on this target.
+group("gtk3") {
+  visibility = [
+    "//chrome/browser/ui/libgtk2ui",
+    "//gpu/gles2_conform_support:gles2_conform_test_windowless",
+    "//remoting/host",
+    "//remoting/host/it2me:remote_assistance_host",
+    "//remoting/host:remoting_me2me_host_static",
+  ]
+  public_configs = [ ":gtk3_internal_config" ]
+}
+
+# Depend on "gtkprint" to get this.
+pkg_config("gtkprint3_internal_config") {
+  packages = [ "gtk+-unix-print-3.0" ]
+}
+
+group("gtkprint3") {
+  visibility = [ "//chrome/browser/ui/libgtk2ui" ]
+  public_configs = [ ":gtkprint3_internal_config" ]
+}

config/ui.gni

@@ -35,6 +35,9 @@ declare_args() {
 
   # Whether the entire browser uses toolkit-views on Mac instead of Cocoa.
   mac_views_browser = false
+
+  # Whether we should use GTKv3 instead of GTKv2.
+  use_gtk3 = false
 }
 
 # Additional dependent variables -----------------------------------------------

linux/system.gyp

@@ -128,7 +128,7 @@
           ],
         },
         {
-          'target_name': 'gtk',
+          'target_name': 'gtk2',
           'type': 'none',
           'toolsets': ['host', 'target'],
           'variables': {
@@ -169,7 +169,7 @@
           ],
         },
         {
-          'target_name': 'gtkprint',
+          'target_name': 'gtkprint2',
           'type': 'none',
           'conditions': [
             ['_toolset=="target"', {
@@ -423,6 +423,74 @@
         }
       ],  # targets
     }],
+    ['use_gtk3==1', {
+      # Hide GTK3 and related dependencies when use_gtk3==0 because the user
+      # might not have the GTK3 headers yet.
+      'targets': [
+        {
+          'target_name': 'gtk3',
+          'type': 'none',
+          'toolsets': ['host', 'target'],
+          'variables': {
+            # gtk requires gmodule, but it does not list it as a dependency
+            # in some misconfigured systems.
+            'gtk_packages': 'gmodule-2.0 gtk+-3.0 gthread-2.0',
+          },
+          'conditions': [
+            ['_toolset=="target"', {
+              'all_dependent_settings': {
+                'cflags': [
+                  '<!@(<(pkg-config) --cflags <(gtk_packages))',
+                ],
+              },
+              'link_settings': {
+                'ldflags': [
+                  '<!@(<(pkg-config) --libs-only-L --libs-only-other <(gtk_packages))',
+                ],
+                'libraries': [
+                  '<!@(<(pkg-config) --libs-only-l <(gtk_packages))',
+                ],
+              },
+            }, {
+              'all_dependent_settings': {
+                'cflags': [
+                  '<!@(pkg-config --cflags <(gtk_packages))',
+                ],
+              },
+              'link_settings': {
+                'ldflags': [
+                  '<!@(pkg-config --libs-only-L --libs-only-other <(gtk_packages))',
+                ],
+                'libraries': [
+                  '<!@(pkg-config --libs-only-l <(gtk_packages))',
+                ],
+              },
+            }],
+          ],
+        },
+        {
+          'target_name': 'gtkprint3',
+          'type': 'none',
+          'conditions': [
+            ['_toolset=="target"', {
+              'direct_dependent_settings': {
+                'cflags': [
+                  '<!@(<(pkg-config) --cflags gtk+-unix-print-3.0)',
+                ],
+              },
+              'link_settings': {
+                'ldflags': [
+                  '<!@(<(pkg-config) --libs-only-L --libs-only-other gtk+-unix-print-3.0)',
+                ],
+                'libraries': [
+                  '<!@(<(pkg-config) --libs-only-l gtk+-unix-print-3.0)',
+                ],
+              },
+            }],
+          ],
+        },
+      ],
+    }],
     ['use_x11==1 and chromeos==0', {
       'targets': [
         {