Add ability to only upload a single Chromium build and check for patch existence

ct/go/util/chromium_builds.go

Index: ct/go/util/chromium_builds.go
diff --git a/ct/go/util/chromium_builds.go b/ct/go/util/chromium_builds.go
index 709bac0c597f4e2a8688dd8747b6def8a5180c13..552fc03c6e8c84f401702f4609ec58995663ac07 100644
--- a/ct/go/util/chromium_builds.go
+++ b/ct/go/util/chromium_builds.go
@@ -41,7 +41,8 @@ func ChromiumBuildDir(chromiumHash, skiaHash, runID string) string {
 // Skia's LKGR hash is used (the hash in Chromium's DEPS file).
 // applyPatches if true looks for Chromium/Skia patches in the temp dir and
 // runs once with the patch applied and once without the patch applied.
-func CreateChromiumBuild(runID, targetPlatform, chromiumHash, skiaHash string, applyPatches bool) (string, string, error) {
+// uploadSingleBuild if true does not upload a 2nd build of Chromium.
+func CreateChromiumBuild(runID, targetPlatform, chromiumHash, skiaHash string, applyPatches, uploadSingleBuild bool) (string, string, error) {
 	// Determine which build dir and fetch target to use.
 	var chromiumBuildDir, fetchTarget string
 	if targetPlatform == "Android" {
@@ -125,7 +126,7 @@ func CreateChromiumBuild(runID, targetPlatform, chromiumHash, skiaHash string, a
 
 	// Check for the applypatch flag and reset and then build again and copy to
 	// google storage.
-	if applyPatches {
+	if applyPatches && !uploadSingleBuild {
 		// Now build chromium without the patches and upload it to Google Storage.
 
 		// Make sure we are starting from a clean slate.
@@ -248,23 +249,27 @@ func resetChromiumCheckout(chromiumSrcDir string) error {
 }
 
 func applyRepoPatches(chromiumSrcDir, runID string) error {
-	// Apply Skia patch.
+	// Apply Skia patch if it exists.
 	skiaDir := filepath.Join(chromiumSrcDir, "third_party", "skia")
 	skiaPatch := filepath.Join(os.TempDir(), runID+".skia.patch")
-	skiaPatchFile, _ := os.Open(skiaPatch)
-	skiaPatchFileInfo, _ := skiaPatchFile.Stat()
-	if skiaPatchFileInfo.Size() > 10 {
-		if err := ApplyPatch(skiaPatch, skiaDir); err != nil {
-			return fmt.Errorf("Could not apply Skia's patch in %s: %s", skiaDir, err)
+	if _, err := os.Stat(skiaPatch); err == nil {
+		skiaPatchFile, _ := os.Open(skiaPatch)
+		skiaPatchFileInfo, _ := skiaPatchFile.Stat()
+		if skiaPatchFileInfo.Size() > 10 {
+			if err := ApplyPatch(skiaPatch, skiaDir); err != nil {
+				return fmt.Errorf("Could not apply Skia's patch in %s: %s", skiaDir, err)
+			}
 		}
 	}
-	// Apply Chromium patch.
+	// Apply Chromium patch if it exists.
 	chromiumPatch := filepath.Join(os.TempDir(), runID+".chromium.patch")
-	chromiumPatchFile, _ := os.Open(chromiumPatch)
-	chromiumPatchFileInfo, _ := chromiumPatchFile.Stat()
-	if chromiumPatchFileInfo.Size() > 10 {
-		if err := ApplyPatch(chromiumPatch, chromiumSrcDir); err != nil {
-			return fmt.Errorf("Could not apply Chromium's patch in %s: %s", chromiumSrcDir, err)
+	if _, err := os.Stat(chromiumPatch); err == nil {
+		chromiumPatchFile, _ := os.Open(chromiumPatch)
+		chromiumPatchFileInfo, _ := chromiumPatchFile.Stat()
+		if chromiumPatchFileInfo.Size() > 10 {
+			if err := ApplyPatch(chromiumPatch, chromiumSrcDir); err != nil {
+				return fmt.Errorf("Could not apply Chromium's patch in %s: %s", chromiumSrcDir, err)
+			}
 		}
 	}
 	return nil