Add Performance podspec (#6526)

FirebasePerformance.podspec.json

@@ -0,0 +1,42 @@
+{
+  "authors": "Google, Inc.",
+  "dependencies": {
+    "FirebaseCore": "~> 6.9",
+    "FirebaseInstallations": "~> 1.5",
+    "FirebaseRemoteConfig": "~> 4.7",
+    "GTMSessionFetcher/Core": "~> 1.1",
+    "GoogleDataTransport": "~> 7.0",
+    "GoogleToolboxForMac/Logger": "~> 2.1",
+    "GoogleToolboxForMac/NSData+zlib": "~> 2.1",
+    "GoogleUtilities/Environment": "~> 6.2",
+    "GoogleUtilities/ISASwizzler": "~> 6.2",
+    "GoogleUtilities/MethodSwizzler": "~> 6.2",
+    "Protobuf": "~> 3.12"
+  },
+  "description": "Firebase Performance provides insights into the performance characteristics of apps",
+  "frameworks": [
+    "CoreTelephony",
+    "QuartzCore",
+    "SystemConfiguration"
+  ],
+  "homepage": "https://firebase.google.com/docs/perf-mon/",
+  "license": {
+    "text": "Copyright 2020 Google",
+    "type": "Copyright"
+  },
+  "name": "FirebasePerformance",
+  "platforms": {
+    "ios": "8.0"
+  },
+  "preserve_paths": [
+    "README.md"
+  ],
+  "source": {
+    "http": "https://dl.google.com/dl/cpdc/ec10178ac6b36ea6/FirebasePerformance-3.3.0.tar.gz"
+  },
+  "summary": "Firebase Performance for iOS",
+  "vendored_frameworks": [
+    "Frameworks/FirebasePerformance.framework"
+  ],
+  "version": "3.3.0"
+}