Handle malformed dumpsys package output.

Some devices produce malformed dumpsys package output, adding in extra
newlines. This change handles a specific version of how this extra
whitespace breaks the parser.

Fixes #1077

core/os/android/adb/adb_data_test.go

@@ -95,7 +95,10 @@ Activity Resolver Table:
 Packages:
   Package [com.google.foo] (ffffffc):
     userId=12345
-    primaryCpuAbi=armeabi-v7a
+    *** extra whitespace on next line is for testing https://github.com/google/agi/issues/1077 ***
+    *** Do not remove it, doing so will make the tests fail ***
+
+primaryCpuAbi=armeabi-v7a
     secondaryCpuAbi=null
     versionCode=902107 minSdk=14 targetSdk=15
     flags=[ HAS_CODE ALLOW_CLEAR_USER_DATA ALLOW_BACKUP ]

core/os/android/adb/installed_package.go

@@ -211,6 +211,7 @@ func (t *treeNode) find(name string) *treeNode {
 
 func parseTabbedTree(str string) *treeNode {
 	head := &treeNode{depth: -1}
+	extraDepth := 0
 	for _, line := range strings.Split(str, "\n") {
 		line = strings.TrimRight(line, "\r")
 		if line == "" {
@@ -219,14 +220,35 @@ func parseTabbedTree(str string) *treeNode {
 
 		// Calculate the line's depth
 		depth := 0
-		for i, r := range line {
+		for _, r := range line {
 			if r == ' ' {
 				depth++
 			} else {
-				line = line[i:]
 				break
 			}
 		}
+		line = line[depth:]
+
+		if line == "" {
+			// A line containing only whitespace probably comes from an extra newline
+			// character being printed before the intended line. So, add the depth that
+			// would have resulted from this empty line to the next line. Example with
+			// front spaces shown as '_':
+			// ...
+			// Known Packages:
+			// _ Package [foo]:
+			// __
+			//Package categories:
+			// ___ category bar
+			// ...
+			// In the above example "Package categories" was meant to be indented by
+			// two spaces, which are present on the previous line.
+			extraDepth += depth
+			continue
+		}
+
+		depth += extraDepth
+		extraDepth = 0
 
 		// Find the insertion point
 		for {