Remove kOzoneTestSingleOverlaySupport.

kOzoneTestSingleOverlaySupport was originally added to test a single
overlay plane when using Ozone.

The code evolved and now passing that parameter enable overlays (not
only a single overlay).

This CL removes the command line flag and uses kEnableHardwareOverlays
instead to enable overlays on Ozone.

BUG=b/29430506

Review-Url: https://codereview.chromium.org/2122303003
Cr-Commit-Position: refs/heads/master@{#405606}

chrome/app/generated_resources.grd

@@ -6567,14 +6567,6 @@ Keep your key file in a safe place. You will need it to create new versions of y
       <message name="IDS_FLAGS_SYNC_SANDBOX_DESCRIPTION" desc="Description for the flag that causes Chrome to use the sandbox (testing) server for Sync.">
         Connects to the testing server for Chrome Sync.
       </message>
-      <if expr="chromeos">
-        <message name="IDS_FLAGS_OZONE_TEST_SINGLE_HARDWARE_OVERLAY" desc="Name of the 'Ozone hardware overlay' lab.">
-          Ozone hardware overlay
-        </message>
-        <message name="IDS_FLAGS_OZONE_TEST_SINGLE_HARDWARE_OVERLAY_DESCRIPTION" desc="Description of the 'Ozone hardware overlay' lab.">
-          Enables compositing with an addition of one hardware overlay when possible.
-        </message>
-      </if>
       <message name="IDS_FLAGS_DATASAVER_PROMPT_NAME" desc="Title for the flag to enable a prompt to install Data Saver when a cellular network is detected." translateable="false">
         Cellular Data Saver Prompt
       </message>

chrome/browser/about_flags.cc

@@ -1512,12 +1512,6 @@ const FeatureEntry kFeatureEntries[] = {
      ENABLE_DISABLE_VALUE_TYPE(switches::kEnableChildAccountDetection,
                                switches::kDisableChildAccountDetection)},
 #endif
-#if defined(OS_CHROMEOS) && defined(USE_OZONE)
-    {"ozone-test-single-overlay-support",
-     IDS_FLAGS_OZONE_TEST_SINGLE_HARDWARE_OVERLAY,
-     IDS_FLAGS_OZONE_TEST_SINGLE_HARDWARE_OVERLAY_DESCRIPTION, kOsCrOS,
-     SINGLE_VALUE_TYPE(switches::kOzoneTestSingleOverlaySupport)},
-#endif  // defined(OS_CHROMEOS) && defined(USE_OZONE)
     {"v8-pac-mojo-out-of-process", IDS_FLAGS_V8_PAC_MOJO_OUT_OF_PROCESS_NAME,
      IDS_FLAGS_V8_PAC_MOJO_OUT_OF_PROCESS_DESCRIPTION, kOsDesktop,
      ENABLE_DISABLE_VALUE_TYPE(switches::kV8PacMojoOutOfProcess,

content/browser/compositor/gpu_process_transport_factory.cc

@@ -235,14 +235,12 @@ CreateOverlayCandidateValidator(gfx::AcceleratedWidget widget) {
   std::unique_ptr<display_compositor::CompositorOverlayCandidateValidator>
       validator;
 #if defined(USE_OZONE)
-  std::unique_ptr<ui::OverlayCandidatesOzone> overlay_candidates =
-      ui::OzonePlatform::GetInstance()
-          ->GetOverlayManager()
-          ->CreateOverlayCandidates(widget);
   base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
-  if (overlay_candidates &&
-      (command_line->HasSwitch(switches::kEnableHardwareOverlays) ||
-       command_line->HasSwitch(switches::kOzoneTestSingleOverlaySupport))) {
+  if (command_line->HasSwitch(switches::kEnableHardwareOverlays)) {
+    std::unique_ptr<ui::OverlayCandidatesOzone> overlay_candidates =
+        ui::OzonePlatform::GetInstance()
+            ->GetOverlayManager()
+            ->CreateOverlayCandidates(widget);
     validator.reset(
         new display_compositor::CompositorOverlayCandidateValidatorOzone(
             std::move(overlay_candidates)));

ui/ozone/platform/drm/host/drm_overlay_manager.cc

@@ -29,8 +29,6 @@ const size_t kMaxCacheSize = 200;
 DrmOverlayManager::DrmOverlayManager(GpuThreadAdapter* proxy,
                                      DrmWindowHostManager* window_manager)
     : proxy_(proxy), window_manager_(window_manager), cache_(kMaxCacheSize) {
-  is_supported_ = base::CommandLine::ForCurrentProcess()->HasSwitch(
-      switches::kOzoneTestSingleOverlaySupport);
   proxy_->RegisterHandlerForDrmOverlayManager(this);
 }
 
@@ -40,8 +38,6 @@ DrmOverlayManager::~DrmOverlayManager() {
 
 std::unique_ptr<OverlayCandidatesOzone>
 DrmOverlayManager::CreateOverlayCandidates(gfx::AcceleratedWidget w) {
-  if (!is_supported_)
-    return nullptr;
   return base::WrapUnique(new DrmOverlayCandidatesHost(this, w));
 }
 

ui/ozone/platform/drm/host/drm_overlay_manager.h

@@ -49,7 +49,6 @@ class DrmOverlayManager : public OverlayManagerOzone {
       const OverlayCandidatesOzone::OverlaySurfaceCandidate& candidate,
       gfx::AcceleratedWidget widget) const;
 
-  bool is_supported_;
   GpuThreadAdapter* proxy_;               // Not owned.
   DrmWindowHostManager* window_manager_;  // Not owned.
 

ui/ozone/public/ozone_switches.cc

@@ -12,10 +12,6 @@ const char kOzonePlatform[] = "ozone-platform";
 // Specify location for image dumps.
 const char kOzoneDumpFile[] = "ozone-dump-file";
 
-// Enable support for a single overlay plane.
-const char kOzoneTestSingleOverlaySupport[] =
-    "ozone-test-single-overlay-support";
-
 // Specifies the size of the primary display at initialization.
 const char kOzoneInitialDisplayBounds[] = "ozone-initial-display-bounds";
 

ui/ozone/public/ozone_switches.h

@@ -14,8 +14,6 @@ OZONE_BASE_EXPORT extern const char kOzonePlatform[];
 
 OZONE_BASE_EXPORT extern const char kOzoneDumpFile[];
 
-OZONE_BASE_EXPORT extern const char kOzoneTestSingleOverlaySupport[];
-
 OZONE_BASE_EXPORT extern const char kOzoneInitialDisplayBounds[];
 
 OZONE_BASE_EXPORT extern const char kOzoneInitialDisplayPhysicalSizeMm[];