Fix "is_swiftshader" feature flag not being set when used via ANGLE

is_swiftshader should be set to true if Chrome is launched with
"--use_gl=swiftshader" or "--use_gl=angle --use_angle=swiftshader".

Bug: b/146423360
Change-Id: I99a510bc92ecabdf5ef6a4954df8c251d83b674b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2186996Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Antonio Maiorano <amaiorano@google.com>
Cr-Commit-Position: refs/heads/master@{#766502}

gpu/command_buffer/service/feature_info.cc

@@ -244,13 +244,16 @@ void FeatureInfo::InitializeBasicState(const base::CommandLine* command_line) {
   feature_flags_.enable_shader_name_hashing =
       !command_line->HasSwitch(switches::kDisableShaderNameHashing);
 
+  const auto useGL = command_line->GetSwitchValueASCII(switches::kUseGL);
+  const auto useANGLE = command_line->GetSwitchValueASCII(switches::kUseANGLE);
+
   feature_flags_.is_swiftshader_for_webgl =
-      (command_line->GetSwitchValueASCII(switches::kUseGL) ==
-       gl::kGLImplementationSwiftShaderForWebGLName);
+      (useGL == gl::kGLImplementationSwiftShaderForWebGLName);
 
   feature_flags_.is_swiftshader =
-      (command_line->GetSwitchValueASCII(switches::kUseGL) ==
-       gl::kGLImplementationSwiftShaderName);
+      (useGL == gl::kGLImplementationSwiftShaderName) ||
+      ((useGL == gl::kGLImplementationANGLEName) &&
+       (useANGLE == gl::kANGLEImplementationSwiftShaderName));
 
   // The shader translator is needed to translate from WebGL-conformant GLES SL
   // to normal GLES SL, enforce WebGL conformance, translate from GLES SL 1.0 to