Chat REST samples (#449)

* Add first chat samples for rest

* Add Chat rest examples

* last message should be 'role:user'

Change-Id: I3e06e9e0ffb553cfc70add5ed0365cb56e9fddff

---------

Co-authored-by: Mark Daoust <markdaoust@google.com>

samples/rest/chat.sh

@@ -0,0 +1,93 @@
+set -eu
+
+SCRIPT_DIR=$(dirname "$0")
+MEDIA_DIR=$(realpath ${SCRIPT_DIR}/../../third_party)
+
+echo "[START chat]"
+# [START chat]
+curl https://generativelanguage.googleapis.com/v1beta/models/gemini-1.5-flash:generateContent?key=$GOOGLE_API_KEY \
+    -H 'Content-Type: application/json' \
+    -X POST \
+    -d '{
+      "contents": [
+        {"role":"user",
+         "parts":[{
+           "text": "Hello"}]},
+        {"role": "model",
+         "parts":[{
+           "text": "Great to meet you. What would you like to know?"}]},
+        {"role":"user",
+         "parts":[{
+           "text": "I have two dogs in my house. How many paws are in my house?"}]},
+      ]
+    }' 2> /dev/null | grep "text"
+# [END chat]
+
+echo "[START chat_streaming]"
+# [START chat_streaming]
+curl https://generativelanguage.googleapis.com/v1beta/models/gemini-1.5-flash:streamGenerateContent?key=$GOOGLE_API_KEY \
+    -H 'Content-Type: application/json' \
+    -X POST \
+    -d '{
+      "contents": [
+        {"role":"user",
+         "parts":[{
+           "text": "Hello"}]},
+        {"role": "model",
+         "parts":[{
+           "text": "Great to meet you. What would you like to know?"}]},
+        {"role":"user",
+         "parts":[{
+           "text": "I have two dogs in my house. How many paws are in my house?"}]},
+      ]
+    }' 2> /dev/null | grep "text"
+# [END chat_streaming]
+
+echo "[START chat_streaming_with_images]"
+# [START chat_streaming_with_images]
+IMG_PATH=${MEDIA_DIR}/organ.jpg
+
+if [[ "$(base64 --version 2>&1)" = *"FreeBSD"* ]]; then
+  B64FLAGS="--input"
+else
+  B64FLAGS="-w0"
+fi
+
+curl https://generativelanguage.googleapis.com/v1beta/models/gemini-1.5-flash:streamGenerateContent?key=$GOOGLE_API_KEY \
+    -H 'Content-Type: application/json' \
+    -X POST \
+    -d '{
+        "contents": [
+            {
+                "role": "user",
+                "parts": [
+                    {
+                        "text": "Hello, I am interested in learning about musical instruments. Can I show you one?"
+                    }
+                ]
+            },
+            {
+                "role": "model",
+                "parts": [
+                    {
+                        "text": "Certainly."
+                    },
+                ]
+            },
+            {
+                "role": "user",
+                "parts": [
+                    {
+                        "text": "Tell me about this instrument"
+                    },
+                    {
+                        "inline_data": {
+                            "mime_type": "image/jpeg",
+                            "data": "'$(base64 $B64FLAGS $IMG_PATH)'"
+                        }
+                    }
+                ]
+            }
+        ]
+    }' 2> /dev/null | grep "text"
+# [END chat_streaming_with_images]