feat(scan): scaffold permission priming in scan view

src/sass/views/tab-scan.scss

@@ -1,4 +1,58 @@
+$scannerBackgroundColor: #060d2d;
+
 #tab-scan {
+  color: #fff;
+  text-align: center;
+  background: transparent none;
+  &-has-problems,
+  &-loading-camera {
+    background-color: $scannerBackgroundColor;
+  }
+  &-has-problems {
+    height: 100%;
+    display: flex;
+    flex-direction: column;
+    align-items: center;
+    justify-content: center;
+
+    .zero-state {
+      &-icon {
+        display: inline-block;
+        width: 50px;
+        height: 50px;
+        border-radius: 50%;
+        padding: 13px;
+        box-shadow: $subtle-box-shadow;
+        background-color: #fff;
+      }
+      &-heading {
+        font-size: 20px;
+        margin: 1rem;
+      }
+      &-description {
+        margin: 0 2rem 120px;
+        opacity: .6;
+        max-width: 300px;
+      }
+      &-tldr {
+        margin: 1rem auto;
+      }
+      &-description,
+      &-tldr {
+        max-width: 300px;
+      }
+      &-cta {
+        position: absolute;
+        bottom: 0;
+        width: 100%;
+        padding-bottom: 6vh;
+      }
+    }
+  }
+  &-loading-camera {
+
+  }
+  &-camera-ready {
     // view background is transparent to show video preview
     background: none transparent;
     .scanner-controls {
@@ -49,7 +103,8 @@
       background-image: url("../img/icon-camera-toggle.svg");
     }
   }
+}
 
 #cordova-plugin-qrscanner-still, #cordova-plugin-qrscanner-video-preview {
-  background-color: #060d2d !important;
+  background-color: $scannerBackgroundColor !important;
 }

www/views/tab-scan.html

@@ -1,8 +1,30 @@
 <ion-view id="tab-scan">
   <ion-nav-bar class="bar-royal">
     <ion-nav-title>{{'Scan' | translate}}</ion-nav-title>
+    <ion-nav-buttons side="primary">
+      <button class="button back-button button-clear ng-hide" ng-click="goBack()" ng-show="canGoBack()">
+        <i class="icon ion-ios-close-empty"></i>
+      </button>
+    </ion-nav-buttons>
   </ion-nav-bar>
   <ion-content scroll="false">
+    <div class="ng-hide" id="tab-scan-has-problems" ng-show="currentState === scannerStates.unauthorized || currentState === scannerStates.denied || currentState === scannerStates.unavailable">
+      <i class="icon zero-state-icon">
+        <img src="img/tab-icons/ico-receive.svg" />
+      </i>
+      <div class="zero-state-heading" translate>Scan QR Codes</div>
+      <div class="zero-state-description" translate>You can scan bitcoin addresses, payment requests, paper wallets, and more.</div>
+      <div class="zero-state-cta">
+        <div class="ng-hide zero-state-tldr" ng-show="currentState === scannerStates.unauthorized" translate>Enable the camera to get started.</div>
+        <div class="ng-hide zero-state-tldr" ng-show="currentState === scannerStates.denied" translate>Enable camera access in your device settings to get started.</div>
+        <div class="ng-hide zero-state-tldr" ng-show="currentState === scannerStates.unavailable" translate>Please connect a camera to get started.</div>
+        <button ng-show="currentState === scannerStates.unauthorized" class="ng-hide button button-standard button-primary" ng-click="attemptActivate">Allow Camera Access</button>
+        <button ng-show="currentState === scannerStates.denied && canOpenSettings" class="ng-hide button button-standard button-primary" ng-click="openSettings">Open Settings</button>
+        <button ng-show="currentState === scannerStates.unavailable" class="ng-hide button button-standard button-primary">Retry Camera</button>
+      </div>
+    </div>
+    <div class="ng-show" id="tab-scan-loading-camera" ng-show="currentState === scannerStates.loading"></div>
+    <div class="ng-hide" id="tab-scan-camera-ready" ng-show="currentState === scannerStates.visible">
       <div class="guides">
         <img class="qr-scan-guides" src="img/bitpay-wallet-qr-scan-guides.svg">
       </div>
@@ -18,5 +40,6 @@
           </i>
         </a>
       </div>
+    </div>
   </ion-content>
 </ion-view>