Turn the utility process image decoder into a Mojo service.

chrome/common/chrome_switches.cc

Index: chrome/common/chrome_switches.cc
diff --git a/chrome/common/chrome_switches.cc b/chrome/common/chrome_switches.cc
index 04f8a2a270c5c79e025af5218f95efad4511452c..9385cbb0e3fb9f62a797ed2f85ca43f56a977fcf 100644
--- a/chrome/common/chrome_switches.cc
+++ b/chrome/common/chrome_switches.cc
@@ -277,6 +277,9 @@ const char kDisableIPv6[]                   = "disable-ipv6";
 const char kDisableMinimizeOnSecondLauncherItemClick[] =
     "disable-minimize-on-second-launcher-item-click";
 
+// Disable using Mojo for utility process services.
+const char kDisableMojoUtilityServices[] = "disable-mojo-utility-services";
+
 // Disables the new bookmark app system.
 const char kDisableNewBookmarkApps[]        = "disable-new-bookmark-apps";
 
@@ -1387,6 +1390,15 @@ bool PdfMaterialUIEnabled() {
   return false;
 }
 
+bool MojoUtilityServicesEnabled() {

[jam, 2015/05/12 23:24:57]

we don't add methods for checking if one switch is enabled. just put this
directly in the three callers

[Anand Mistry (off Chromium), 2015/05/13 04:35:11]

The main reason I have this here is so that this can be disabled easily if a
regression is found in a release branch (and I can add an enable flag if
needed). The other reason is so that I can apply the same check (with same
ability to back out) to other utility process services I change.  Is that ok?

+  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
+          kDisableMojoUtilityServices)) {
+    return false;
+  }
+
+  return true;
+}
+
 bool SettingsWindowEnabled() {
 #if defined(OS_CHROMEOS)
   return !base::CommandLine::ForCurrentProcess()->HasSwitch(