Test Runner: Really reuse displays with --bot-mode.

The prior design didn't pass the correct flag to the subprocess.
Instead add a new --reuse-displays flag that forces display reuse
on in ANGLE tests. Pass the new flag to the child processes when
running with --bot-mode.

Bug: angleproject:3162
Change-Id: I5f62125d83d339b5e8b2506b4ca4656976f7398e
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2419638
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>

src/tests/test_utils/ANGLETest.cpp

@@ -170,11 +170,11 @@ const char *GetColorName(GLColor color)
 }
 
 // Always re-use displays when using --bot-mode in the test runner.
-bool gBotModeEnabled = false;
+bool gReuseDisplays = false;
 
 bool ShouldAlwaysForceNewDisplay()
 {
-    if (gBotModeEnabled)
+    if (gReuseDisplays)
         return false;
 
     // We prefer to reuse config displays. This is faster and solves a driver issue where creating
@@ -313,7 +313,7 @@ TestPlatformContext gPlatformContext;
 constexpr uint32_t kWindowReuseLimit = 50;
 
 constexpr char kUseConfig[]                      = "--use-config=";
-constexpr char kBotMode[]                        = "--bot-mode";
+constexpr char kReuseDisplays[]                  = "--reuse-displays";
 constexpr char kEnableANGLEPerTestCaptureLabel[] = "--angle-per-test-capture-label";
 
 void SetupEnvironmentVarsForCaptureReplay()
@@ -1358,9 +1358,9 @@ void ANGLEProcessTestArgs(int *argc, char *argv[])
         {
             SetSelectedConfig(argv[argIndex] + strlen(kUseConfig));
         }
-        if (strncmp(argv[argIndex], kBotMode, strlen(kBotMode)) == 0)
+        if (strncmp(argv[argIndex], kReuseDisplays, strlen(kReuseDisplays)) == 0)
         {
-            gBotModeEnabled = true;
+            gReuseDisplays = true;
         }
         if (strncmp(argv[argIndex], kEnableANGLEPerTestCaptureLabel,
                     strlen(kEnableANGLEPerTestCaptureLabel)) == 0)

src/tests/test_utils/runner/TestSuite.cpp

@@ -1030,6 +1030,9 @@ bool TestSuite::launchChildTestProcess(const std::vector<TestIdentifier> &testsI
     args.push_back(filterFileArg.c_str());
     args.push_back(resultsFileArg.c_str());
 
+    // TODO(jmadill): Remove this once migrated. http://anglebug.com/3162
+    args.push_back("--reuse-displays");
+
     for (const std::string &arg : mGoogleTestCommandLineArgs)
     {
         args.push_back(arg.c_str());