Allow only responsive websites to install as a web app on mobile.

chrome/browser/android/banners/app_banner_data_fetcher_android.cc

Index: chrome/browser/android/banners/app_banner_data_fetcher_android.cc
diff --git a/chrome/browser/android/banners/app_banner_data_fetcher_android.cc b/chrome/browser/android/banners/app_banner_data_fetcher_android.cc
index eaba3f14a8bfb05da7108d7d9ff12c542504b59a..1862556ff53cf4609665176547c2e9b8118c4ce6 100644
--- a/chrome/browser/android/banners/app_banner_data_fetcher_android.cc
+++ b/chrome/browser/android/banners/app_banner_data_fetcher_android.cc
@@ -4,11 +4,26 @@
 
 #include "chrome/browser/android/banners/app_banner_data_fetcher_android.h"
 
+#include <vector>
+
+#include "base/strings/string_util.h"
 #include "chrome/browser/android/banners/app_banner_infobar_delegate_android.h"
+#include "chrome/browser/banners/app_banner_debug_log.h"
 #include "chrome/browser/infobars/infobar_service.h"
 #include "chrome/browser/ui/android/infobars/app_banner_infobar_android.h"
+#include "chrome/common/chrome_constants.h"
+#include "chrome/common/render_messages.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 
+namespace {
+
+const char kMetaViewportTagName[] = "viewport";
+const char kMetaViewportWidthDevice[] = "width=device-width";
+const char kMetaViewportInitialScaleInt[] = "initial-scale=1";
+const char kMetaViewportInitialScaleFloat[] = "initial-scale=1.0";
+
+}  // anonymous namespace
+
 namespace banners {
 
 AppBannerDataFetcherAndroid::AppBannerDataFetcherAndroid(
@@ -37,6 +52,23 @@ bool AppBannerDataFetcherAndroid::ContinueFetching(
   return FetchIcon(image_url);
 }
 
+bool AppBannerDataFetcherAndroid::OnMessageReceived(
+    const IPC::Message& message) {
+  bool handled = true;
+  IPC_BEGIN_MESSAGE_MAP(AppBannerDataFetcherAndroid, message)
+    IPC_MESSAGE_HANDLER(ChromeViewHostMsg_DidRetrieveMetaTagContent,
+                        OnDidRetrieveMetaTagContent)
+    IPC_MESSAGE_UNHANDLED(handled = false)
+  IPC_END_MESSAGE_MAP()
+  return handled;
+}
+
+void AppBannerDataFetcherAndroid::HandleWebApp(
+    content::WebContents* web_contents) {
+  Send(new ChromeViewMsg_RetrieveMetaTagContent(routing_id(), validated_url_,
+                                                kMetaViewportTagName));
+}
+
 std::string AppBannerDataFetcherAndroid::GetAppIdentifier() {
   return native_app_data_.is_null()
       ? AppBannerDataFetcher::GetAppIdentifier() : native_app_package_;
@@ -66,8 +98,61 @@ void AppBannerDataFetcherAndroid::ShowBanner(const SkBitmap* icon,
     if (infobar)
       RecordDidShowBanner("AppBanner.NativeApp.Shown");
   }
-  InfoBarService::FromWebContents(web_contents)
-      ->AddInfoBar(make_scoped_ptr(infobar));
+  if (infobar) {
+    InfoBarService::FromWebContents(web_contents)
+        ->AddInfoBar(make_scoped_ptr(infobar));
+  }
+}
+
+// Ideally, we should be able to get this information more directly. For now, we
+// parse the retrieved meta viewport tag (if any), and look for the necessary
+// strings to determine if the page will scale with the viewport.
+void AppBannerDataFetcherAndroid::OnDidRetrieveMetaTagContent(
+    bool success,
+    const std::string& tag_name,
+    const std::string& tag_content,
+    const GURL& expected_url) {
+  bool is_responsive = false;
+  if (success && tag_name == kMetaViewportTagName &&
+      validated_url_ == expected_url &&
+      tag_content.size() <= chrome::kMaxMetaTagAttributeLength) {
+    std::string local_tag_content;
+    std::vector<std::string> content_tokens;
+
+    // Perform the following steps:
+    // 1. strip spaces from the viewport content.
+    // 2. convert the content to lower case.
+    // 3. split the viewport content by commas.
+    // 4. search for the required strings.
+    base::RemoveChars(tag_content, " ", &local_tag_content);
+    base::StringToLowerASCII(&local_tag_content);
+    Tokenize(local_tag_content, ",", &content_tokens);
+
+    for (const auto& property : content_tokens) {
+      if (property == kMetaViewportWidthDevice ||
+          property == kMetaViewportInitialScaleInt ||
+          property == kMetaViewportInitialScaleFloat) {
+        is_responsive = true;
+        break;
+      }
+    }
+  }
+
+  content::WebContents* web_contents = GetWebContents();
+  if (!is_responsive) {
+    OutputDeveloperNotShownMessage(web_contents, kMetaViewportTagError);
+    Cancel();
+    return;
+  }
+
+  if (!CheckFetcherIsStillAlive(web_contents)) {
+    OutputDeveloperNotShownMessage(web_contents,
+                                   kUserNavigatedBeforeBannerShown);
+    Cancel();
+    return;
+  }
+
+  AppBannerDataFetcher::HandleWebApp(web_contents);
 }
 
 }  // namespace banners