Query tiles : Implement fake tile provider

This CL adds a fake tile provider that fakes out the backend and provides
a set of example topics and images. The images are fetched directly from
the URLs by image fetcher in Java layer.

TBR=dtrainor@chromium.org

Bug: 1069864
Change-Id: I441aa5d8e63c6c5924199748f3b7d175228dbee7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2145678Reviewed-by: David Trainor <dtrainor@chromium.org>
Reviewed-by: Min Qin <qinmin@chromium.org>
Commit-Queue: Shakti Sahu <shaktisahu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#760245}

chrome/android/chrome_java_sources.gni

@@ -1387,6 +1387,7 @@ chrome_java_sources = [
   "java/src/org/chromium/chrome/browser/provider/ChromeBrowserProviderSuggestionsCursor.java",
   "java/src/org/chromium/chrome/browser/provider/SearchColumns.java",
   "java/src/org/chromium/chrome/browser/push_messaging/PushMessagingServiceObserver.java",
+  "java/src/org/chromium/chrome/browser/query_tiles/FakeTileProvider.java",
   "java/src/org/chromium/chrome/browser/query_tiles/QueryTileSection.java",
   "java/src/org/chromium/chrome/browser/query_tiles/TileProviderFactory.java",
   "java/src/org/chromium/chrome/browser/rappor/RapporServiceBridge.java",

chrome/android/java/src/org/chromium/chrome/browser/query_tiles/QueryTileSection.java

@@ -49,6 +49,7 @@ public class QueryTileSection {
         mSubmitQueryCallback = performSearchQueryCallback;
         if (!isFeatureEnabled()) return;
 
+        TileProviderFactory.setFakeTileProvider(new FakeTileProvider());
         mTileProvider = TileProviderFactory.getForProfile(profile);
         TileConfig tileConfig = new TileConfig.Builder().setUmaPrefix(UMA_PREFIX).build();
         mTileCoordinator = ImageTileCoordinatorFactory.create(mQueryTileSectionView.getContext(),

chrome/android/java/src/org/chromium/chrome/browser/query_tiles/TileProviderFactory.java

@@ -31,6 +31,12 @@ public class TileProviderFactory {
         sTileProvider = provider;
     }
 
+    // TODO(shaktisahu): Remove this function once we have the real provider.
+    public static void setFakeTileProvider(FakeTileProvider provider) {
+        if (sTileProvider != null) return;
+        sTileProvider = provider;
+    }
+
     @NativeMethods
     interface Natives {
         TileProvider getForProfile(Profile profile);