[Chromecast] Enable use_sysroot by default for Linux Cast builds.

This CL modifies the Ozone platforms built on Chromecast builds. It
updates the logic in common.gypi to match the logic in ozone.gni.
ozone_platform_gbm still does not build, but this is not needed for our
platform, so this will not be an issue for Cast builds.

BUG=504446
BUG=559708

Bug: b/25865950

Review URL: https://codereview.chromium.org/1477633002

Cr-Commit-Position: refs/heads/master@{#362209}

2 files changed, 34 insertions, 26 deletions

diff --git a/build/common.gypi b/build/common.gypi
index 454cc5d..3b92489 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -295,11 +295,8 @@
             'mips_arch_variant%': 'r1',
           }],
 
-          # The system root for linux compiles.
-          # Not used when chromecast=1 since ozone_platform_gbm doesn't
-          # currently build against the linux sysroot
-          # TODO(sbc): http://crbug.com/559708
-          ['OS=="linux" and chromeos==0 and chromecast==0 and use_sysroot==1', {
+          # The system root for linux builds.
+          ['OS=="linux" and chromeos==0 and use_sysroot==1', {
             # sysroot needs to be an absolute path otherwise it generates
             # incorrect results when passed to pkg-config
             'conditions': [
@@ -664,6 +661,10 @@
       # build only explicitly selected platforms.
       'ozone_auto_platforms%': 1,
 
+      # Disable the display for a chromecast build. Set to 1 perform an audio-
+      # only build.
+      'disable_display%': 0,
+
       # If this is set clang is used as host compiler, but not as target
       # compiler. Always do this by default.
       'host_clang%': 1,
@@ -1885,9 +1886,6 @@
           }],
         ],
       }],
-      ['chromecast==1 and OS!="android"', {
-        'ozone_platform_cast%': 1
-      }],
       ['OS=="linux"', {
         'clang%': 1,
       }],  # OS=="mac"
@@ -2383,12 +2381,28 @@
       ['use_ozone==1 and ozone_auto_platforms==1', {
         # Use headless as the default platform.
         'ozone_platform%': 'headless',
-
-        # Build all platforms whose deps are in install-build-deps.sh.
-        # Only these platforms will be compile tested by buildbots.
-        'ozone_platform_gbm%': 1,
         'ozone_platform_headless%': 1,
-        'ozone_platform_egltest%': 1,
+        'conditions': [
+          ['chromecast==1', {
+            'conditions': [
+              ['disable_display==0', {
+                # Enable the Cast ozone platform on all A/V Cast builds.
+                'ozone_platform_cast%': 1,
+                'conditions': [
+                  ['OS=="linux" and target_arch!="arm"', {
+                    'ozone_platform_egltest%': 1,
+                    'ozone_platform_ozonex%': 1,
+                  }],
+                ],
+              }],
+            ],
+          }, {
+            # Build all platforms whose deps are in install-build-deps.sh.
+            # Only these platforms will be compile tested by buildbots.
+            'ozone_platform_gbm%': 1,
+            'ozone_platform_egltest%': 1,
+          }],
+        ],
       }],
 
       ['desktop_linux==1 and use_aura==1 and use_x11==1', {
diff --git a/ui/ozone/ozone.gni b/ui/ozone/ozone.gni
index a1fe2f8..8e33f80 100644
--- a/ui/ozone/ozone.gni
+++ b/ui/ozone/ozone.gni
@@ -29,31 +29,25 @@ declare_args() {
   ozone_platform_headless = false
 
   if (ozone_auto_platforms) {
+    # Use headless as the default platform.
+    ozone_platform = "headless"
+    ozone_platform_headless = true
+
     if (is_chromecast) {
-      ozone_platform_headless = true
-      if (disable_display) {
-        # Audio-only builds should use the "headless" platform by default.
-        ozone_platform = "headless"
-      } else {
-        # Builds with video should default to the "cast" platform.
+      if (!disable_display) {
         ozone_platform_cast = true
-        ozone_platform = "cast"
 
-        # For desktop Chromecast builds, override the default "cast" platform with
-        # --ozone_platform=egltest
+        # For desktop Chromecast builds, override the default "headless" platform
+        # with --ozone-platform=egltest
         if (target_os == "linux" && target_cpu != "arm") {
           ozone_platform_egltest = true
           ozone_platform_ozonex = true
         }
       }
     } else {
-      # Use headless as the default platform.
-      ozone_platform = "headless"
-
       # Build all platforms whose deps are in install-build-deps.sh.
       # Only these platforms will be compile tested by buildbots.
       ozone_platform_gbm = true
-      ozone_platform_headless = true
       ozone_platform_egltest = true
     }
   }