Re-add kUseGpuInTests flag in WebRTC browser tests.

chrome/browser/media/chrome_webrtc_apprtc_browsertest.cc

Index: chrome/browser/media/chrome_webrtc_apprtc_browsertest.cc
diff --git a/chrome/browser/media/chrome_webrtc_apprtc_browsertest.cc b/chrome/browser/media/chrome_webrtc_apprtc_browsertest.cc
index 6eada11a6506618863c658c141f6d268337aeadb..f494e797fb31b0050bdc611d441a76995488fd1d 100644
--- a/chrome/browser/media/chrome_webrtc_apprtc_browsertest.cc
+++ b/chrome/browser/media/chrome_webrtc_apprtc_browsertest.cc
@@ -55,8 +55,10 @@ class WebRtcApprtcBrowserTest : public WebRtcTestBase {
   void SetUpCommandLine(base::CommandLine* command_line) override {
     EXPECT_FALSE(command_line->HasSwitch(switches::kUseFakeUIForMediaStream));
 
-    // Use fake devices in order to run on VMs.
-    command_line->AppendSwitch(switches::kUseFakeDeviceForMediaStream);
+    // The video playback will not work without a GPU, so force its use here.
+    command_line->AppendSwitch(switches::kUseGpuInTests);
+    base::CommandLine::ForCurrentProcess()->AppendSwitch(
+        switches::kUseFakeDeviceForMediaStream);
   }
 
   void TearDown() override {