Reland "Revert PowerSaveBlockerLinux [2/4]"

This reverts commit abf93b0b.

Reason for revert: a few WakeLockTest are failing probably due to this. Let me try to revert this to see how it'll go.
Sample failing build:
https://ci.chromium.org/p/chromium/builders/ci/Linux%20Tests%20%28dbg%29%281%29/85013

Original change's description:
> Revert "Revert  PowerSaveBlockerLinux [2/4]"
> 
> This reverts commit bbfce899.
> 
> Reason for revert: Issue should be fixed after https://chromium-review.googlesource.com/c/chromium/src/+/1937507/ lands
> 
> Original change's description:
> > Revert  PowerSaveBlockerLinux [2/4]
> > 
> > and the subsequent  PowerSaveBlockerLinux [3/4] and  PowerSaveBlockerLinux [4/4] patches
> > 
> > This reverts commit 2fdeba1b. ("Rewrite PowerSaveBlockerLinux [2/4]")
> > This reverts commit 38fdf074. ("Rewrite PowerSaveBlockerLinux [3/4]")
> > This reverts commit 3bc463b4. ("Rewrite PowerSaveBlockerLinux [4/4]")
> > 
> > The patch caused timeouts in WakeLockTest.ChangeType() and other tests in the services_unittests on
> > Linux Tests (dbg). More details in crbug/1027852.
> > 
> > TBR=thomasanderson@chromium.org
> > 
> > Bug: 1013812,1027852
> > Change-Id: I7688c72f9d9d6c12ff3731f3abde6a05508cfbeb
> > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1932357
> > Commit-Queue: Tim Schumann <tschumann@chromium.org>
> > Reviewed-by: Tim Schumann <tschumann@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#718447}
> 
> TBR=thomasanderson@chromium.org,tschumann@chromium.org
> 
> # Not skipping CQ checks because original CL landed > 1 day ago.
> 
> Bug: 1013812, 1027852
> Change-Id: I84a6681cc8ec347587d38f0f5f38ed628e624274
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1937509
> Reviewed-by: Thomas Anderson <thomasanderson@chromium.org>
> Reviewed-by: Tim Schumann <tschumann@chromium.org>
> Commit-Queue: Thomas Anderson <thomasanderson@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#720760}

TBR=thomasanderson@chromium.org,tschumann@chromium.org

Change-Id: I317fd312d0c44b3e59bbada94df3200fa44ae3ac
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 1013812, 1027852
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1947513Reviewed-by: Makoto Shimazu <shimazu@chromium.org>
Commit-Queue: Makoto Shimazu <shimazu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#720843}

services/device/wake_lock/power_save_blocker/BUILD.gn

@@ -22,6 +22,12 @@ source_set("power_save_blocker") {
 
   sources = [
     "power_save_blocker.h",
+    "power_save_blocker_android.cc",
+    "power_save_blocker_chromeos.cc",
+    "power_save_blocker_mac.cc",
+    "power_save_blocker_stub.cc",
+    "power_save_blocker_win.cc",
+    "power_save_blocker_x11.cc",
   ]
 
   public_deps = [
@@ -36,40 +42,48 @@ source_set("power_save_blocker") {
     deps += [ "//dbus" ]
   }
 
+  if (use_x11) {
+    configs += [ "//build/config/linux:x11" ]
+    if (!is_chromeos) {
+      configs += [ "//build/config/linux:xscrnsaver" ]
+    }
+    deps += [
+      "//ui/gfx",
+      "//ui/gfx/x",
+    ]
+  }
+
+  # Dealing with power_save_blocker_{x11,stub}.cc is a little complicated
+  # given the interaction between os_chromeos and the feature flags for X11 and
+  # ozone, so do it all in one spot.
+  #
+  # stub implementation is only used at the moment non-chromeOS Ozone platforms
+  # such as Chromecast.
+  if (is_chromeos || !use_ozone) {
+    sources -= [ "power_save_blocker_stub.cc" ]
+  }
+
+  if (is_chromeos || !use_x11 || !use_dbus) {
+    sources -= [ "power_save_blocker_x11.cc" ]
+  }
+
   if (is_android) {
-    sources += [ "power_save_blocker_android.cc" ]
     deps += [ ":jni_headers" ]
     public_deps += [ "//ui/android" ]
-  } else if (is_chromeos) {
-    sources += [ "power_save_blocker_chromeos.cc" ]
+  }
+
+  if (is_chromeos) {
     deps += [
       "//chromeos/dbus/power",
       "//chromeos/dbus/power:power_manager_proto",
     ]
-  } else if (is_linux && use_dbus) {
-    sources += [ "power_save_blocker_linux.cc" ]
-    deps += [
-      "//dbus",
-      "//ui/gfx",
-    ]
-    if (use_x11) {
-      configs += [
-        "//build/config/linux:x11",
-        "//build/config/linux:xscrnsaver",
-      ]
-      deps += [ "//ui/gfx/x" ]
-    }
-  } else if (is_mac) {
-    sources += [ "power_save_blocker_mac.cc" ]
+  }
+
+  if (is_mac) {
     libs = [
       "CoreFoundation.framework",
       "IOKit.framework",
     ]
-  } else if (is_win) {
-    sources += [ "power_save_blocker_win.cc" ]
-  } else {
-    # Fuchsia and non-DBus Linux.
-    sources += [ "power_save_blocker_stub.cc" ]
   }
 }
 

services/device/wake_lock/power_save_blocker/power_save_blocker.h

@@ -61,6 +61,13 @@ class PowerSaveBlocker {
   // };
   scoped_refptr<Delegate> delegate_;
 
+#if defined(USE_X11)
+  // Since display sleep prevention also implies system suspend prevention, for
+  // the Linux FreeDesktop API case, there needs to be a second delegate to
+  // block system suspend when screen saver / display sleep is blocked.
+  scoped_refptr<Delegate> freedesktop_suspend_delegate_;
+#endif
+
   scoped_refptr<base::SequencedTaskRunner> ui_task_runner_;
   scoped_refptr<base::SequencedTaskRunner> blocking_task_runner_;